Ailments & Treatments

In Brief (Distance)

Myopia. Blurry vision in one eye or both eyes may be a symptom of myopia (nearsightedness), along with squinting, eye strain and headaches. Myopia is the most common refractive error and causes objects in the distance to become blurred.

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In Brief (General)

• Hyperopia. Blurred vision from hyperopia (farsightedness) is when distant objects can be seen sharply but your eyes can't focus properly on close-up objects or doing so causes unusual eye strain and fatigue. In cases of severe farsightedness, even distant objects may appear blurred
• Myopia. Blurry vision in one eye or both eyes may be a symptom of myopia (nearsightedness), along with squinting, eye strain and headaches. Myopia is the most common refractive error and causes objects in the distance to become blurred.
• Astigmatism. Blurred vision at all distances often is a symptom of astigmatism. A type of refractive error, astigmatism usually is caused by an irregularly shaped cornea.
• With astigmatism, light rays fail to come to a single focus point on the retina to produce clear vision, regardless of how far away the viewed object is from the eye. Astigmatism, like nearsightedness and farsightedness, can be corrected with eyeglasses, contact lenses or refractive surgery.

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In Brief (Near)

Hyperopia. Blurred vision from hyperopia (farsightedness) is when distant objects can be seen sharply but your eyes can't focus properly on close-up objects or doing so causes unusual eye strain and fatigue. In cases of severe farsightedness, even distant objects may appear blurred.

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In Brief (Distance)

A pinguecula is a yellowish, slightly raised thickening of the conjunctiva on the white part of the eye (sclera), close to the edge of the cornea. Pingueculae are non-cancerous bumps on the eyeball and typically occur on top of the middle part of the sclera — the part that's between your eyelids and therefore is exposed to the sun. Usually pingueculae affect the surface of the sclera that's closer to the nose, but they can occur on the outer sclera (closer to the ear) as well.

Symptoms

• Usually don’t cause any symptoms
• May cause burning sensation due to dry eye
• May cause redness with irritation

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In Brief (Distance)

Most bumps on the eyelid are styes. A stye (external hordeolum) is an inflamed oil gland on the edge of your eyelid, where the lash meets the lid. It appears as a red, swollen bump that looks like a pimple. It is often tender to the touch.

Symptoms

In addition to the red, swollen bump, other possible symptoms include:

• A gritty, scratchy sensation, as if there is a foreign body in your eye
• Sensitivity to light
• Tearing of your eye
• Tenderness of the eyelid

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In Brief (Distance)

Cataract is the term to denote clouding or opacification of the natural lens of the eye.

Symptoms

• Blurred vision or cloudy vision
• Glare
• Decreased brightness
• Gradual painless progressive course

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In Brief (Distance)

Cellulitis is a common bacterial skin infection. Cellulitis may first appear as a red, swollen area that feels hot and tender to the touch. The redness and swelling often spread rapidly. Cellulitis is usually painful. Cellulitis usually affects the surface of your skin, but it may also affect the underlying tissues of your skin. Cellulitis can also spread to your lymph nodes and bloodstream.

Symptoms

• Pain and tenderness in the affected area
• Redness or inflammation of your skin
• A skin sore or rash that appears and grows quickly
• A tight, glossy, swollen appearance of the skin
• A feeling of warmth in the affected area
• A central area that has an abscess with pus formation
• A fever

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In Brief (Distance)

Central retinal vein occlusion (CRVO) is a blockage of the main vein in the retina. The blockage causes the walls of the vein to leak blood and excess fluid into the retina. When this fluid collects in the macula (the area of the retina responsible for central vision), vision becomes blurry. Two types: Non-ischemic CRVO and ischemic CRVO.

Symptoms

• Blurring of vision, sometimes complete vision loss
• Painless
• Happens suddenly or worsens over several hours

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In Brief (Distance)

In central serous retinopathy (sometimes called central serous choroidopathy), fluid builds up under the retina and distorts vision. Fluid leakage is believed to come from a tissue layer with blood vessels under the retina, called the choroid. Often associated with stress and steroids.

Symptoms

• Distorted central vision, blind spot in centre
• Blurred or dim vision

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In Brief (Distance)

Symptoms

• A lump on the top or bottom eyelid
• Localized swelling of the eyelid
• Localized pain
• Redness
• Tenderness
• Crusting of the eyelid margins
• Burning in the eye
• Droopiness of the eyelid
• Scratchy sensation on the eyeball (itching)
• Blurred vision
• Mucous discharge in the eye
• Irritation of the eye
• Light sensitivity
• Tearing
• Discomfort during blinking
• Sensation of a foreign body in the eye

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In Brief (Distance)

Choroidal neovascular membranes (CNVM) are new blood vessels that grow beneath the retina and disrupt vision. These blood vessels grow in an area called the choroid, the area between the retina and the sclera (the white part of your eye). The choroid supplies oxygen and nutrients to the eye. CNVM occur when new blood vessels start to grow in the choroid and break through the barrier between the choroid and the retina. When CNVM leak in the retina, they cause vision loss.

Symptoms

• Painless vision loss
• Blank spots in vision, especially central vision
• Distorted vision
• Size of objects may appear different for each eye
• Colors lose brightness and may look different
• Light flashes or flickering in central vision

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In Brief (Distance)

A coloboma describes conditions where normal tissue in or around the eye is missing from birth. Coloboma term comes from a Greek word meaning “curtailed”. Depending on the tissue involved, it may be

• Eyelid coloboma
• Lens coloboma
• Macular coloboma
• Optic nerve coloboma
• Uveal coloboma
• Chorioretinal coloboma

Symptoms

• A coloboma of the iris will be visibly noticeable due to the keyhole or cat-eye appearance of the pupil.
• An eyelid coloboma will also be noticeable due to a notch or defect in the eyelid.
• Other types can cause vision loss depending on their size and location
• A child with a coloboma affecting the macula or the optic nerve will likely have reduced vision.
• children who are missing a part of their retina will have a “field defect,” which means that they will not have vision in a specific location (for instance, the upper part of the field of vision).
• Sometimes children with a coloboma have increased sensitivity to light.

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In Brief (Distance)

Color blindness or colour vision problem occurs when you are unable to see colors in a normal way. Most commonly, color blindness (also known as color deficiency) happens when someone cannot distinguish between certain colors, usually between greens and reds, and occasionally blues.

Symptoms

• Trouble seeing colors and the brightness of colors in the usual way
• Inability to tell the difference between shades of the same or similar colors, particularly red and green, or blue and yellow.
• Mostly does not affect sharpness of vision

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Causes

• Viruses
• Bacteria (such as gonorrhea or chlamydia)
• Irritants such as shampoos, dirt, smoke, and pool chlorine
• Allergies like dust, pollen, or a special type of allergy that affects some contact lens wearers

Symptoms

• Redness in the white of the eye or inner eyelid
• Increased amount of tears
• Thick yellow discharge that crusts over the eyelashes, especially after sleep
• Green or white discharge from the eye
• Itchy eyes
• Burning eyes
• Blurred vision
• Increased sensitivity to light

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In Brief

Contact Lens-Related Eye Infections

The most common infection related to contact lens use is keratitis, an infection of the cornea (the clear, round dome covering the eye's iris and pupil). Keratitis can have multiple causes, including herpes, bacteria, fungus and microbes (such as acanthamoeba—a very difficult infection to treat). Keratitis is the most serious complication of contact lens wear. In severe cases, it can lead to corneal scarring that impairs vision, and may lead to the need for a cornea transplant.

Symptoms

• Blurry vision
• Unusual redness of the eye
• Pain in the eye
• Tearing or discharge from the eye
• Increased light sensitivity
• Sensation of something in your eye.

Infections

Factors contributing to contact-lens related infections

• Use of extended-wear lenses
• Sleeping in your contact lenses
• Reduced tear exchange under the lens
• Environmental factors
• Poor hygiene, including poor maintenance of contact lens cases or reusing or topping off contact lens solution

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In Brief

A corneal abrasion (scratched cornea or scratched eye) is one of the most common eye injuries. It is a superficial damage to the cornea which is the transparent part of the eye. Corneal abrasions result from a disruption or loss of cells in the top layer of the cornea, called the corneal epithelium.

Symptoms

• Significant discomfort
• Red eyes
• Watering of eyes
• Hypersensitivity to light.

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In Brief

Corneal dystrophy is a group of rare hereditary disorders characterised by bilateral abnormal deposition of substances in the transparent front part of the eye called the cornea.

Corneal dystrophies are characterized by the accumulation of foreign material in one or more of the five layers of the cornea. The material may cause the cornea to lose its transparency, potentially causing loss of vision or blurred vision.

There are more than 20 different types of corneal dystrophies. They are generally grouped into three categories, depending on the part of the cornea that they affect:

• Anterior or superficial corneal dystrophies affect the outermost layers of the cornea: the epithelium and the Bowman membrane.
• Stromal corneal dystrophies affect the stroma, the middle and thickest layer of the cornea.
• Posterior corneal dystrophies affect the innermost parts of the cornea: the endothelium and the Descemet membrane. The most common posterior corneal dystrophy is Fuchs’ dystrophy,

Symptoms

• May cause significant decrease in vision
• Usually seen in first or second decade of life
• Grayish white lines, circles or clouding of cornea

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In Brief

Corneal erosion affects the cornea, the clear dome covering the front of the eye. The cornea is composed of five layers. The outermost layer is the epithelium. When the epithelium does not stay attached correctly to the corneal tissue below, including the layer called the Bowman's layer or the basement membrane, this can cause a condition called corneal erosion. If the problem occurs repeatedly, it is called recurrent corneal erosion.

Symptoms

• Mild to severe pain
• Light sensitivity
• Feeling of something in the eye
• Blurred vision
• Watery eyes
• Dryness

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In Brief

A corneal laceration is a cut on the cornea, the clear front window of the eye. It is usually caused by something sharp flying into the eye or something striking the eye with significant force, like a metallic hand tool. A corneal laceration is deeper than a corneal abrasion, cutting partially or fully through the cornea. If the corneal laceration is deep enough (called a full thickness laceration), it will cut completely through the cornea and cause a ruptured globe, a tear in the outer surface of the eyeball itself.

Symptoms

• Severe pain
• Tearing
• Sensitivity to light
• Blurred or decreased vision
• Bleeding (blood in the eye)
• The feeling that there is something in the eye.

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In Brief

A corneal ulcer is an open sore on the cornea - the clear front window of the eye. The cornea covers the iris (the colored portion of the eye) and the round pupil, much like a watch crystal covers the face of a watch. A corneal ulcer usually results from an eye infection, though it can be caused by severe dry eye or other eye disorders.

Symptoms

• Redness of the eye
• Severe pain and soreness of the eye
• The feeling of having something in your eye
• Tearing
• Pus or other discharge
• Blurred vision
• Sensitivity to light
• Swelling of the eyelids
• A white spot on your cornea that you may or may not be able to see when looking in the mirror.

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In Brief

Cytomegalovirus Retinitis

Cytomegalovirus (CMV) Retinitis is an acquired immunodeficiency syndrome (AIDS)-related opportunistic infection that can lead to blindness. CMV retinitis occurred with higher frequency prior to the advent of antiretroviral therapy, but has since been decreasing in well-developed countries, although still remains a prevalent condition in developing countries. It is a full thickness retinal infection that can lead to necrosis and retinal breaks and detachments.

Most patients are asymptomatic, but may have floaters, flashes (photopsias), blind spots (scotomata). Pain and photophobia are uncommon.

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In Brief

Crossed eyes (or strabismus) occur when a person’s eyes are not able to align on the same point at the same time, and appear to be misaligned or pointed in different directions.

Symptoms

• Eyes that do not move together
• Unsymmetrical points of reflection in each eye
• Tilting the head to one side
• Inability to gauge depth
• Squinting with only one eye

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In Brief

Cloud shape in vision

A dark or gray spot or cloud shaped spot or speck that passes across your field of vision and moves as you move your eye is known as floater. Floaters are very common and may look like clouds, strands, webs, spots, squiggles, wavy lines or other shapes. As your eye ages, the gelatinous vitreous humor begins to liquefy in the center of the gel. Floaters are caused by the undissolved vitreous humor that floats in the liquid vitreous. Sometimes, a "shower of floaters" is a sign of a serious condition, particularly if you also see flashes of light.

Symptoms

• Spots in your vision that appear as dark specks or knobby, transparent strings of floating material
• Spots that move when you move your eyes, so when you try to look at them, they move quickly out of your visual field
• Spots that are most noticeable when you look at a plain bright background, such as a blue sky or a white wall
• Spots that eventually settle down and drift out of the line of vision

When to see a doctor

• Many more eye floaters than usual
• A sudden onset of new floaters
• Flashes of light
• Darkness on the sides of your vision (peripheral vision loss)

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In Brief

Color vision problem

Color blindness or colour vision problem occurs when you are unable to see colors in a normal way. Most commonly, color blindness (also known as color deficiency) happens when someone cannot distinguish between certain colors, usually between greens and reds, and occasionally blues.

Symptoms

• Trouble seeing colors and the brightness of colors in the usual way.
• Inability to tell the difference between shades of the same or similar colors, particularly red and green, or blue and yellow.
• Mostly does not affect sharpness of vision.

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In Brief

Clouding of the eye’s surface

Corneal opacities are eye problems that can lead to scarring or clouding of the cornea, which decreases vision. Corneal opacities can cause anything from minor irritation to vision problems and even blindness. In some cases it can be present from birth.

Symptoms

• Redness and swelling of the eye tissues and eyelid
• Tearing
• Blurred vision
• Irritation
• Sensitivity to light
• Sensation of something in the eye
• Eye discharge
• Milky or cloudy area on the cornea
• Vision loss

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In Brief

Crusty Eye Lid

Symptoms

• Itchy, sore and red eyelids that stick together
• Crusty or greasy eyelashes
• A burning, gritty sensation in your eyes
• Increased sensitivity to light (photophobia)
• Swollen eyelid margins
• Finding contact lenses uncomfortable to wear
• Abnormal eyelash growth or loss of eyelashes in severe cases

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In Brief

The retina is the light-sensitive tissue lining the back of our eye. The middle of our eye is filled with a clear gel called vitreous that is attached to the retina. As we get older, the vitreous may shrink and pull on the retina. When this happens, you may notice what look like flashing lights, lightning streaks or the sensation of seeing “stars.” These are called flashes. Usually, the vitreous moves away from the retina without causing problems. But sometimes the vitreous pulls hard enough to tear the retina in one or more places. Fluid may pass through a retinal tear, lifting the retina off the back of the eye — much as wallpaper can peel off a wall. When the retina is pulled away from the back of the eye like this, it is called a retinal detachment.

Symptoms

• A sudden increase in size and number of floaters, indicating a retinal tear may be occurring.
• A sudden appearance of flashes, which could be the first stage of a retinal tear or detachment.
• Having a shadow appear in the periphery (side) of your field of vision.
• Seeing a gray curtain moving across your field of vision.
• A sudden decrease in your vision.

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In Brief

Distorted vision is when familiar objects look wavy or bent incorrectly.

Distorted vision may be associated with:

• Age-Related Macular Degeneration (AMD)
• Astigmatism
• Conjunctivitis (Pink Eye)
• Kerataconus
• Macular Edema
• Macular Hole
• Macular Pucker

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In Brief

Endothelial keratoplasty (EK) is a cornea transplant technique that is the preferred way to restore vision when the inner cell layer of the cornea stops working properly from Fuchs’ dystrophy, bullous keratopathy, iridocorneal endothelial (ICE) syndrome, or other endothelial disorders. EK selectively replaces only the diseased layer of the cornea, leaving healthy areas intact.

The most common type of EK procedure is known as DSEK. In this procedure the surgeon implants the back 20-30% of the donor cornea into the patient’s eye. Patients without other eye problems usually achieve average vision of 20/30 or better within a couple of months. The risk of rejection from DSEK is around 12 percent, whereas full thickness transplants have around a 20 percent rejection risk.

Steps:

• The surgeon removes the diseased inner cell layer of the cornea
• The surgeon implants healthy donor tissue through a small incision
• The surgeon then uses an air bubble to unfold and position the donor tissue against the patient’s cornea
• The small incision is either self-sealing or may be closed with a suture or two.

Compared with a traditional full thickness transplant, endothelial keratoplasty provides the following advantages:

• The eye remains much stronger and less prone to injury
• Visual recovery is much faster
• Minimal activity restrictions are required
• Minimal change is required in glasses prescription

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In Brief

Discharge

Discharge is mucus, pus or excessive tearing coming from the eye.

Discharge from eye may be associated with:

• Bacterial Keratitis
• Blocked Tear Duct
• Conjunctivitis (Pink Eye)
• Corneal Ulcer
• Dry Eye
• Fungal Keratitis
• Herpes Keratitis

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In Brief

Depth perception problems

Depth perception is an important part of your vision, allowing you to sense the distance and speed of objects. Depth perception is especially important while driving, so a sudden or gradual loss of depth perception can be quite unsettling.

Causes of poor depth perception in children:

• Strabismus (crossed eyes)
• Amblyopia (“lazy eye”)
• Optic Nerve Hypoplasia

Causes of poor depth perception in adults:

• Anisometropia – eyes with differing refractive errors
• A cataract in only one eye
• Macular degeneration or cataracts that diminish color vision or visual contrasts

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Causes

DOUBLE VISION / DIPLOPIA

• Cornea problems - keratoconus
• Herpes zoster
• Corneal scars
• Lens problems-cataract
• Myasthenia gravis
• Graves disease

Symptoms

• Misalignment of one or both eyes (a "wandering eye" or "cross-eyed" appearance)
• Pain with eye movements in one or both eyes
• Pain around the eyes, such as in the temples or eyebrows
• Headache
• nausea
• Weakness in the eyes or anywhere else
• Droopy eyelids

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In Brief

Pathologic eyelid drooping, also called ptosis, may occur due to trauma, age, or various medical disorders. This condition can affect one (unilateral ptosis) or both (bilateral ptosis) eyes, it may come and go, or it might be permanent. It can be present at birth (known as congenital ptosis) or you can develop it later in life (known as acquired ptosis).

Depending on the severity of the condition, drooping eyelids can block or greatly reduce vision depending on how much it obstructs the pupil. In most cases, the condition will resolve, either naturally or through medical intervention.

Symptoms

• Visible drooping of upper eyelid
• Can block vision if eyelid covers the pupillary area through which light enters the eye.
• Can be present from birth (congenital ptosis) in which case lid crease may be absent
• Frequent eyebrow raising, head tilting may be present

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In Brief

Dry eyelids affect many people, especially those who already have issues with dry skin. Dry, flaky skin can sometimes be embarrassing, especially if you suffer from eczema or psoriasis.

Dry, scaly, or flaky skin on your eyelids may be the worst of these conditions, as it can be extremely uncomfortable, irritating, and unattractive.

Causes

• Eczema
• Blepharitis
• Atopic dermatitis
• Allergic reaction
• Indoor allergens
• Dry eye syndrome
• Sjogren’s syndrome

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In Brief

When you blink, a film of tears spreads over the eye, making the surface of the eye smooth and clear. Without this tear film, good vision would not be possible. Sometimes people don't produce enough tears or the right quality of tears to keep their eyes healthy and comfortable. This condition is known as dry eye.

Symptoms

• Stinging or burning eyes
• Scratchiness
• Stringy mucus in or around the eyes
• Excessive eye irritation from smoke or wind
• Excess tearing
• Discomfort when wearing contact lenses

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In Brief

Diabetic retinopathy, the most common diabetic eye disease, occurs when blood vessels in the retina change. Sometimes these vessels swell and leak fluid or even close off completely. In other cases, abnormal new blood vessels grow on the surface of the retina. Diabetic retinopathy usually affects both eyes. People who have diabetic retinopathy often don't notice changes in their vision in the disease's early stages. But as it progresses, diabetic retinopathy usually causes vision loss that in many cases cannot be reversed.

Types:

• Non-proliferative diabetic retinopathy
• Proliferative diabetic retinopathy

Symptoms

• Spots, dots or cobweb-like dark strings floating in your vision (called floaters)
• Blurred vision
• Vision that changes periodically from blurry to clear
• Blank or dark areas in your field of vision
• Poor night vision
• Colors appear washed out or different
• Vision loss

Diabetic retinopathy symptoms usually affect both eyes.

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In Brief

Drusen are yellow deposits under the retina, the light-sensitive tissue at the back of the eye. Drusen are made up of lipids, a fatty protein. While drusen likely do not cause age-related macular degeneration (AMD), their presence increases a person’s risk of developing AMD.

There are different kinds of drusen. “Hard” drusen are small, distinct and far away from one another. This type of drusen may not cause vision problems for a long time, if at all.

“Soft” drusen are large and cluster closer together. Their edges are not as clearly defined as hard drusen. This soft type of drusen increases the risk for AMD.

Drusen can also occur in the optic nerve. These drusen are made up of protein and calcium salts and generally appear in both eyes. Unlike the drusen associated with AMD, optic nerve drusen (also known as optic disc drusen) are not related to aging and often appear in children. Optic nerve drusen usually do not affect vision, but some patients with these drusen may lose peripheral (side) vision.

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In Brief

Madarosis is a condition that results in the loss of eyelashes, sometimes eyebrows. The term "madarosis" is Greek for the word "madao" which means "to fall off." It originally was a disease of only losing eyelashes but it currently is the loss of both eyelashes and eyebrows. Eyebrows and eyelashes are both important in the prevention of bacteria and other foreign objects from entering the eye.

Madarosis is not a critical or severe condition. The main symptom and sign of madarosis is the loss of hair from the eyelids, eyebrows, or eyelashes

Symptoms

• Swollen, itchy, red, burning eyelids
• Loss of hair from other parts of the body, mainly the scalp
• Weight gain or palpitation if there is a thyroid problem

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In Brief

Eyelash particles ,atypical

Blepharitis is a common and ongoing condition where the eyelids become inflamed (swollen), with oily particles and bacteria coating the eyelid margin near the base of the eyelashes. There are dry or sticky crusts on the eyelashes. This annoying condition causes irritation, itchiness, redness, and stinging or burning of the eyes.

Symptoms

• Itchy, sore and red eyelids that stick together
• Crusty or greasy eyelashes
• A burning, gritty sensation in your eyes
• Increased sensitivity to light (photophobia)
• Swollen eyelid margins
• Finding contact lenses uncomfortable to wear
• Abnormal eyelash growth or loss of eyelashes in severe cases

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In Brief

Eyelid cleft

An eyelid cleft is a defect in the eyelid, mostly present since birth. A coloboma describes conditions where normal tissue in or around the eye is missing from birth, hence this condition is also known as coloboma of eyelid. A piece of the upper or lower eyelid is missing.

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In Brief Eyelid turns in

Entropion is a condition in which your eyelid turns inward so that your eyelashes and skin rub against the eye surface. This causes irritation and discomfort.

When you have entropion, your eyelid may be turned in all the time or only when you blink hard or squeeze your eyelids shut. Entropion is more common in older adults, and it generally affects only the lower eyelid.

Artificial tears and lubricating ointments can help relieve symptoms of entropion. But usually surgery is needed to fully correct the condition. Left untreated, entropion can cause damage to the transparent covering in the front part of your eye (cornea), eye infections and vision loss.

Symptoms

The signs and symptoms of entropion result from the friction of your eyelashes and outer eyelid against the surface of your eye. You may experience:

• The feeling that something is in your eye
• Eye redness
• Eye irritation or pain
• Sensitivity to light and wind
• Watery eyes (excessive tearing)
• Mucous discharge and eyelid crusting
• Decreased vision

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In Brief Eyelid turns out

Ectropion is a condition in which your eyelid turns outward. This leaves the inner eyelid surface exposed and prone to irritation.

Ectropion is more common in older adults, and it generally affects only the lower eyelid. In severe ectropion, the entire length of the eyelid is turned out. In less severe ectropion, only one segment of the eyelid sags away from the eye.

Artificial tears and lubricating ointments can help relieve symptoms of ectropion. But usually surgery is needed to fully correct the condition.

Symptoms

If you have ectropion, your lower lid pulls away from your eye and tears don't drain properly into the puncta. The resulting signs and symptoms can include:

• Watery eyes (excessive tearing)- Without proper drainage, your tears may pool and constantly flow over your eyelids.
• Excessive dryness- Ectropion can cause your eyes to feel dry, gritty and sandy.
• Irritation- Stagnant tears or dryness can irritate your eyes, causing a burning sensation and redness in your eyelids and the whites of your eyes.
• Sensitivity to light- Stagnant tears or dry eyes can irritate the surface of the cornea, making you sensitive to light.

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In Brief - Eyes are different color

The terms to describe different colored eyes are heterochromia iridis and heterochromia iridum. "Iridis" and "iridum" refer to the iris of the eye. The iris is the thin, circular structure that surrounds the pupil and contains the pigment melanin, which gives our eyes their distinctive color.

The amount of melanin in the iris determines whether we have blue eyes, green eyes, hazel eyes or brown eyes. Blue eyes have the least amount of melanin in the iris; brown eyes have the most.

Heterochromia usually is benign. In other words, it is not an eye disease, and it does not affect visual acuity.

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In Brief - Eyes don’t point in same direction

Strabismus is a visual problem in which the eyes are not aligned properly and point in different directions. One eye may look straight ahead, while the other eye turns inward, outward, upward, or downward. The eye turn may be consistent, or it may come and go. Which eye is straight (and which is misaligned) may switch or alternate.

Esotropia is used to denote the condition when eyes turns inward and exotropia is used to denote the condition when eyes turn outward.

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In Brief

Strabismus is a visual problem in which the eyes are not aligned properly and point in different directions. One eye may look straight ahead, while the other eye turns inward, outward, upward, or downward. The eye turn may be consistent, or it may come and go. Which eye is straight (and which is misaligned) may switch or alternate.

Esotropia is used to denote the condition when eyes turns inward and exotropia is used to denote the condition when eyes turn outward.

Symptoms

• Itching
• Redness
• Burnin
• Clear, watery discharge

Eye Allergy Triggers

• Outdoor allergens, such as pollens from grass, trees and weeds
• Indoor allergens, such as pet dander, dust mites and mold
• Irritants, such as cigarette smoke, perfume and diesel exhaust

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In Brief

Hyperopia. Blurred vision from hyperopia (farsightedness) is when distant objects can be seen sharply but your eyes can't focus properly on close-up objects or doing so causes unusual eye strain and fatigue. In cases of severe farsightedness, even distant objects may appear blurred.

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In Brief

Causes

• Eye allergies
• Blepharitis
• Dry eyes
• Memobian gland dysfunction
• Contact lens users

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In Brief

Iridocorneal Endothelial Syndrome (ICE) syndrome is a unique ophthalmic disorder that involves an irregular corneal endothelium that can lead to varying degrees of corneal edema, iris atrophy, and secondary angle-closure glaucoma.

ICE syndrome is a group of disorders with three clinical variants:

• Chandler Syndrome
• Essential / Progressive Iris Atrophy
• Iris Nevus / Cogan-Reese Syndrome

The initial presentation of ICE syndrome patients may be due to monocular pain (from corneal edema or elevated intraocular pressure from angle-closure), blurry vision, or iris changes.

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In Brief

Ischemic optic neuropathy (ION) is a sudden loss of central vision, side vision or both due to a decreased or interrupted blood flow to the eye’s optic nerve.

In order to see, the optic nerve carries impulses from the eye to the brain, where they are interpreted as images. The optic nerve is made up of a million tiny, delicate nerve fibers that are like wires. Many blood vessels nourish the optic nerve with blood rich in oxygen and nutrition. Without a healthy, functioning optic nerve, vision would not be possible.

Some ophthalmologists may describe ischemia of the optic nerve as a “stroke at the back of the eye.”

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In Brief

Keratitis is an inflammation of the cornea — the clear, dome-shaped tissue on the front of your eye that covers the pupil and iris. Keratitis is sometimes caused by an infection involving bacteria, viruses, fungi or parasites. Noninfectious keratitis can be caused by a minor injury, wearing your contact lenses too long or other noninfectious diseases.

Symptoms

• Pain
• Blurry vision
• Photophobia
• Red eye
• Tearing
• Discharge
• Foreign body sensation

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In Brief

Keratoconus (KC, KCN, KTCN) is a disorder of the eye which results in progressive thinning of the cornea. This may result in blurry vision, double vision, nearsightedness, astigmatism, and light sensitivity. Usually both eyes are affected. In more severe cases a scarring or a circle may be seen within the cornea.

While the cause is unknown, it is believed to occur due to a combination of genetic, environmental, and hormonal factors. About seven percent of those affected have a family history of the condition. Proposed environmental factors include rubbing the eyes and allergies.

The underlying mechanism involves changes of the cornea to a cone shape. Diagnosis is by examination with a slit lamp.

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• An eye that wanders inward or outward
• Eyes that appear to not work together
• Poor depth perception
• Squinting or shutting an eye
• Head tilting

Causes

• Muscle imbalance (strabismus)
• Difference in sharpness of vision between the eyes (refractive anisometropia)

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Low vision is a loss of eyesight that makes everyday tasks difficult. A person with low vision may find it difficult or impossible to accomplish activities such as reading, writing, shopping, watching television, driving a car or recognizing faces.

When vision cannot be improved with regular eyeglasses, medicine or surgery, people with low vision need help to learn how to make the most of their remaining sight and keep their independence. Losing vision does not mean giving up your activities, but it does mean finding new ways of doing them.

Large appearance of objects that are actually smaller

Micropsia is a condition affecting human visual perception in which objects are perceived to be smaller than they actually are. Micropsia can be caused by optical factors (such as wearing glasses), by distortion of images in the eye (such as optically, via swelling of the cornea or from changes in the shape of the retina such as from retinal edema, macular degeneration, or central serous retinopathy), by changes in the brain (such as from traumatic brain injury, epilepsy,migraines, prescription drugs, and illicit drugs), and from psychological factors. Dissociative phenomena are linked with micropsia, which may be the result of brain-lateralization disturbance.

Micropsia is also commonly reported when the eyes are fixating at (convergence), or focussing at (accommodation), a distance closer than that of the object in accord with Emmert's law. Specific types of micropsia include hemimicropsia, a form of micropsia that is localized to one half of the visual field and can be caused by brain lesions in one of the cerebral hemispheres.

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When the vitreous gel pulls on the retina, you may see what look like flashing lights or lightning streaks. These are called flashes. You may have experienced this same sensation if you have ever been hit in the eye and seen "stars." The flashes of light can appear off and on for several weeks or months.

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Macular edema is the build-up of fluid in the macula, an area in the center of the retina. The retina is the light-sensitive tissue at the back of the eye and the macula is the part of the retina responsible for sharp, straight-ahead vision. Fluid buildup causes the macula to swell and thicken, which distorts vision.

Macular edema occurs when there is abnormal leakage and accumulation of fluid in the macula from damaged blood vessels in the nearby retina. A common cause of macular edema is diabetic retinopathy, a disease that can happen to people with diabetes. Macular edema can also occur after eye surgery, in association with age-related macular degeneration, or as a consequence of inflammatory diseases that affect the eye. Any disease that damages blood vessels in the retina can cause macular edema.

The primary symptom of macular edema is blurry or wavy vision near or in the center of your field of vision. Colors might also appear washed out or faded. Most people with macular edema will have symptoms that range from slightly blurry vision to noticeable vision loss. If only one eye is affected, you may not notice your vision is blurry until the condition is well-advanced.

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In Brief

Causes

• Innervational
  • Supranuclear
  • Nuclear
  • Nerve
  • Synapse
• Muscle anomalies
  • Maldevelopment (e.g. Hypertrophy, atrophy/dystrophy)
  • Malinsertion
  • Scarring secondary to alignment surgery
  • Muscle diseases (e.g. Myasthenia gravis)
• Orbital anomalies
  • Tumor (e.g. rhabdomyosarcoma)
  • Excess fat behind globe (e.g. thyroid conditions)
  • Bone fracture
  • Check ligament (e.g. Brown's syndrome, or Superior tendon sheath syndrome)

Selected disorders

• Congenital fourth nerve palsy
• Duane syndrome
• Internuclear ophthalmoplegia
• Nystagmus
• Ophthalmoparesis
• Opsoclonus
• Sixth (abducent) nerve palsy

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A macular hole is a small break in the macula, located in the center of the eye's light-sensitive tissue called the retina. The macula provides the sharp, central vision we need for reading, driving, and seeing fine detail. A macular hole can cause blurred and distorted central vision.

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A macular pucker is scar tissue that has formed on the eye’s macula, located in the center of the light-sensitive tissue called the retina. The macula provides the sharp, central vision we need for reading, driving, and seeing fine detail. A macular pucker can cause blurred and distorted central vision.

Macular pucker is also known as epiretinal membrane, preretinal membrane, cellophane maculopathy, retina wrinkle, surface wrinkling retinopathy, premacular fibrosis, and internal limiting membrane disease.

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Macular telangiectasia (Mac Tel) leads to abnormalities of capillaries of the fovea or perifoveal region associated with loss outer nuclear layers and ellipsoid zone that can progress to cystic cavitation-like changes in all retinal layers, or development of full-thickness macular hole or subretinal neovascularization in advanced stages.

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Marfan syndrome is an inherited disorder that affects connective tissue — the fibers that support and anchor your organs and other structures in your body. Marfan syndrome most commonly affects the heart, eyes, blood vessels and skeleton.

People with Marfan syndrome are usually tall and thin with disproportionately long arms, legs, fingers and toes. If your aorta — the large blood vessel that carries blood from your heart to the rest of your body — is affected, the condition can become life-threatening.

Treatment usually includes medications to keep your blood pressure low to reduce the strain on your aorta. Regular monitoring to check for damage progression is vital. Many people with Marfan syndrome eventually require preventive surgery to repair the aorta.

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Microvascular cranial nerve palsy (MCNP) is a neurological condition involving the small blood vessels that affects the muscles that move the eyes. With MCNP, there is a blockage of blood flow to the nerves between the brain stem and muscles within the eye socket, as well as other nerves that affect visual function.

With MCNP, you may not be able to move your eyes in one or more directions, depending on the muscles affected, and you may experience double vision.

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A migraine can cause severe throbbing pain or a pulsing sensation, usually on just one side of the head. It's often accompanied by nausea, vomiting, and extreme sensitivity to light and sound.

Migraine attacks can cause significant pain for hours to days and can be so severe that the pain is disabling.

Warning symptoms known as aura may occur before or with the headache. These can include flashes of light, blind spots, or tingling on one side of the face or in your arm or leg.

Medications can help prevent some migraines and make them less painful.

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MG is a neuromuscular disorder that’s usually caused by an autoimmune problem. Autoimmune disorders occur when your immune system mistakenly attacks healthy tissue. In this condition, antibodies, which are proteins that normally attack foreign, harmful substances in the body, attack the neurotransmitter substance acetylcholine, which is a crucial substance for communication between nerve cells and muscles. This results in muscle weakness.

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Blurry vision in one eye or both eyes may be a symptom of myopia (nearsightedness), along with squinting, eye strain and headaches. Myopia is the most common refractive error and causes objects in the distance to become blurred.

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A nevus (plural, nevi) in the eye is a common, benign, pigmented growth, similar to a mole on your skin. A nevus can occur either in the front of your eye, around the iris or colored part of the eye, or beneath the retina in the back of the eye. A nevus beneath the retina is called a choroidal nevus. Sometimes it is called a "freckle in the eye."

While most nevi are harmless, they still need to be watched regularly because, like a skin mole, an eye nevus could possibly develop into an ocular melanoma, or cancer of the eye.

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It is the involuntary movement of the eyes

• Innervational
  • Supranuclear
  • Nuclear
  • Nerve
  • Synapse
• Muscle anomalies
  • Maldevelopment (e.g. Hypertrophy, atrophy/dystrophy)
  • Malinsertion
  • Scarring secondary to alignment surgery
  • Muscle diseases (e.g. Myasthenia gravis)
• Orbital anomalies
  • Tumor (e.g. rhabdomyosarcoma)
  • Excess fat behind globe (e.g. thyroid conditions)
  • Bone fracture
  • Check ligament (e.g. Brown's syndrome, or Superior tendon sheath syndrome)

Selected disorders

• Congenital fourth nerve palsy
• Duane syndrome
• Internuclear ophthalmoplegia
• Nystagmus
• Ophthalmoparesis
• Opsoclonus
• Sixth (abducent) nerve palsy

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Difficulty in vision at night

Causes

• Retinitis pigmentosa
• Vitamin A deficiency
• Glaucoma
• Glaucoma medications that work by constricting the pupil
• Cataracts
• Diabetes
• Keratoconus

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The term ocular hypertension usually refers to any situation in which the pressure inside the eye, called intraocular pressure, is higher than normal. Eye pressure is measured in millimeters of mercury (mm Hg). Normal eye pressure ranges from 10-21 mm Hg. Ocular hypertension is an eye pressure of greater than 21 mm Hg.

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Ocular melanoma (melanoma in or around the eye) is a type of cancer that develops in the cells that produce pigment — the substance that gives your skin, hair and eyes color. Just as you can develop melanoma on your skin, you can also develop it in your eye. Although it is the most common eye cancer in adults, ocular melanoma is rare.

Symptoms-In its early stages, ocular melanoma may not cause any symptoms. Because most melanomas develop in the part of the eye you cannot see, you may not know if you have a melanoma.

When ocular melanoma symptoms do occur, they can include a dark spot on the iris, blurred vision, the sensation of flashing lights, a change in the shape of the pupil and/or loss of vision in the affected eye.

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The optic nerve, also known as cranial nerve II, is a paired nerve that transmits visualinformation from the retina to the brain. The optic nerve is derived from optic stalks during the seventh week of development and is composed of retinal ganglion cell axons and glial cells. In humans, the optic nerve extends from the optic disc to the optic chiasm and continues as the optic tract to the lateral geniculate nucleus, pretectal nuclei, and superior colliculus.

Functions- The optic nerve transmits all visual information including brightness perception, color perception and contrast (visual acuity). It also conducts the visual impulses that are responsible for two important neurological reflexes: the light reflex and the accommodation reflex. The light reflex refers to the constriction of both pupils that occurs when light is shone into either eye; the accommodation reflex refers to the swelling of the lens of eye that occurs when one looks at a near object as in reading (lens adjusts to near vision).

The eye's blind spot is a result of the absence of photoreceptors in the area of the retina where the optic nerve leaves the eye.

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The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or conesoverlying the optic disc, it corresponds to a small physiological blind spot in each eye.

The ganglion cell axons form the optic nerve after they leave the eye. The optic disc represents the beginning of the optic nerve and is the point where the axons of retinal ganglion cells come together. The optic disc is also the entry point for the major blood vessels that supply the retina. The optic disc in a normal human eye carries from 1-1.2 million neurons from the eye towards the brain.

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In the early or mild stage of primary open-angle glaucoma, there are no symptoms. Because of the silent nature of primary open-angle glaucoma, people do not usually have any visual complaints until late in the course of the disease. By the time one would notice vision loss or blind spots, the late or severe stage of glaucoma may have been reached and significant amounts of irreversible optic nerve damage may have already occurred. Again, this is why screening for the disease early on is so important. The earlier the diagnosis is made, the better the odds of successful treatment.

There are no outward signs of primary open-angle glaucoma. The main signs are the presence of a thinned (atrophied) optic nerve and the presence of an open angle, both of which can be seen using specialized instruments during an eye examination.

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Photokeratitis or ultraviolet keratitis is a painful eye condition caused by exposure of insufficiently protected eyes to the ultraviolet(UV) rays from either natural (e.g. intense sunlight) or artificial (e.g. the electric arc during welding) sources. Photokeratitis is akin to a sunburn of the cornea and conjunctiva, and is not usually noticed until several hours after exposure.

Symptoms include increased tears and a feeling of pain, likened to having sand in the eyes.

PAIN OR DISCOMFORT AROUND THE EYES

Causes

• Optic neuritis
• Sinusitis
• Stye

PAIN OR DISCOMFORT IN THE EYES

Causes

• Blepharitis
• Conjunctivitis
• Corneal abrasion
• Glaucoma
• Iritis

Associated symptoms

• Decreased vision
• Discharge, which can be clear, or thick and colored
• Foreign body sensation -- the feeling that something is in the eye, whether real or imagined
• Headache
• Light sensitivity
• Nausea or vomiting
• Red eye or pink eye
• Tearing
• The eye being crusted shut after sleep due to discharge

PAIN OR DISCOMFORT IN THE EYELID

Causes

• Blepharitis
• Stye
• Trauma

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Peripheral vision problem- peripheral vision problems mean that you don't have a normal, wide-angle field of vision, even though your central vision may be fine.

Moderate and severe cases of peripheral vision loss create the sensation of seeing through a narrow tube, a condition commonly referred to as "tunnel vision."

Symptoms of peripheral vision loss also can include difficulty seeing in dim light and decreased ability to navigate while you are walking.

Causes

• Glaucoma
• Retinitis pigmentosa
• Eye strokes or occlusions
• Detached retina
• Brain damage from stroke, disease or injury
• Neurological damage such as from optic neuritis
• Compressed optic nerve head (papilledema)
• Concussions (head injuries)*

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Mydriasis is the dilation of the pupil. Non-physiological causes of mydriasis include disease, trauma, or the use of drugs. Normally, as part of the pupillary light reflex, the pupil dilates in the dark and constricts in the light to respectively improve vividity at night and to protect the retina from sunlight damage during the day. A mydriaticpupil will remain excessively large even in a bright environment. The excitation of the radial fibres of the iris which increases the pupillary aperture is referred to as a mydriasis. More generally, mydriasis also refers to the natural dilation of pupils, for instance in low light conditions or under sympathetic stimulation.

An informal term for mydriasis is blown pupil, and is used by medical providers. It is usually used to refer to a fixed, unilateral mydriasis, which could be a symptom of raised intracranial pressure.

Pupil,small- senile miosis (a reduction in the size of a person's pupil in old age)

Diseases

• Horner's syndrome
• Hemorrhage into pons (intracranial hemorrhage)
• Hereditary disorders
• Cluster Headaches with ptosis
• Iridocyclitis
• Fatal familial insomnia

Pupil unresponsive to light- pupils which are not reactive to light.

• Acute glaucoma
• Aneurysm compressing the third ranial nerve
• Atropine
• Brain herniation
• Brain tumour
• Cardiac arrest
• Cerebral bleed
• Glaucoma
• Ipratropium
• Previous surgery
• Trauma

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Leukocoria literally means "white pupil." It occurs when the pupil (the round hole in the colored part of the eye) is white rather than the usual black causeleukocoria including cataract, retinal detachment, retinopathy of prematurity, retinal malformation, intraocular infection endophthalmitis), retinal vascular abnormality, and intraocular tumor (retinoblastoma).

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Pigment Dispersion Syndrome- Pigment dispersion syndrome (PDS) is an affliction of the eye that can lead to a form of glaucoma known as pigmentary glaucoma. It takes place when pigment cells slough off from the back of the iris and float around in the aqueous humor. Over time, these pigment cells can accumulate in the anterior chamber in such a way that it can begin to clog the trabecular meshwork (the major site of aqueous humour drainage), which can in turn prevent the aqueous humour from draining and therefore increases the pressure inside the eye. With PDS, the intra ocular pressure tends to spike at times and then can return to normal. Exercise has been shown to contribute to spikes in pressure as well. When the pressure is great enough to cause damage to the optic nerve, this is called pigmentary glaucoma. As with all types of glaucoma, when damage happens to the optic nerve fibers, the vision loss that occurs is irreversible and painless.

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Pinguecula and Pterygium-A pinguecula (pin-GWEK-yoo-lah) is a yellowish, slightly raised thickening of the conjunctiva on the white part of the eye (sclera), close to the edge of the cornea.

Causes -Ultraviolet radiation from the sun is the primary cause of the development of pingueculae, but frequent exposure to dust and wind also appear to be be risk factors. Dry eye disease also may be a contributing factor and can promote the growth of pingueculae.

Pterygium most often refers to a benign growth of the conjunctiva. A pterygium commonly grows from the nasal side of the conjunctiva. It is usually present in the palpebral fissure. It is associated with and thought to be caused by ultraviolet-light exposure (e.g., sunlight), low humidity, and dust. The predominance of pterygis on the nasal side is possibly a result of the sun's rays passing laterally through the cornea, where it undergoes refraction and becomes focused on the limbic area.

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Causes

• Viruses
• Bacteria (such as gonorrhea or chlamydia)
• Irritants such as shampoos, dirt, smoke, and pool chlorine
• Allergies, like dust, pollen or a special type of allergy that affects some contact lens wearers

Symptoms

• Redness in the white of the eye or inner eyelid
• Increased amount of tears
• Thick yellow discharge that crusts over the eyelashes, especially after sleep
• Green or white discharge from the eye
• Itchy eyes
• Burning eyes
• Blurred vision
• Increased sensitivity to light

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When people develop presbyopia, they find they need to hold books, magazines, newspapers, menus and other reading materials at arm's length in order to focus properly. When they perform near work, such as embroidery or handwriting, they may develop headaches, eye strain or feel fatigued.

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Ptosis is a drooping or falling of the upper eyelid. The drooping may be worse after being awake longer, when the individual's muscles are tired

• Neurogenic ptosis which includes oculomotor nerve palsy, Horner's syndrome, Marcus Gunn jaw winking syndrome, third cranial nerve misdirection.
• Myogenic ptosis which includes oculopharyngeal muscular dystrophy, myasthenia gravis, myotonic dystrophy, ocular myopathy, simple congenital ptosis, blepharophimosis syndrome
• Aponeurotic ptosis which may be involutional or post-operative
• Mechanical ptosis which occurs due to edema or tumors of the upper lid
• Neurotoxic ptosis which is a classic symptom of envenomation by elapid snakes such as cobras, kraits.

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Retinal detachment is a disorder of the eye in which the retina separates from the layer underneath Symptoms include an increase in the number of floaters, flashes of light, and worsening of the outer part of the visual field. This may be described as a curtain over part of the field of vision

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Retinal holes associated with a condition called lattice vitreoretinal degeneration, or thinning of the retina. If the patient is asymptomatic, most studies have suggested that it is safe to observe the retinal hole without any treatment. By asymptomatic, we mean that the patient is not experiencing any new symptoms of floaters, cobwebs, shadows, or flashing lights.

However, if the patient is symptomatic, then we seal the retinal hole using a "welding" technique with a laser.

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A patient with an acute retinal tear may experience the sudden onset of black spots or “floaters” in the affected eye. This can have the appearance of someone shaking pepper in your vision. Flashes of light (Photopsia) are another common symptom.

If there is associated vitreous hemorrhage (bleeding in the clear cavity of the eye) or retinal detachment, additional symptoms can include blurred vision or a shadow as if curtains are closing in from the peripheral (side) vision. However, in some cases, a retinal tear may not manifest any noticeable symptoms.

Risk factors are not required to develop a retinal tear, but they make the likelihood greater. These factors include:

dvanced age

• Degree of myopia (nearsightedness)
• Associated lattice degeneration (thin patches in the retina)
• Trauma
• Family history of retinal tears or detachment
• Prior eye surgery

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Retinal vein occlusion is a blockage of the small veins that carry blood away from the retina. The retina is the layer of tissue at the back of the inner eye that converts light images to nerve signals and sends them to the brain.

Causes

• Retinal vein occlusion is most often caused by hardening of the arteries (atherosclerosis) and the formation of a blood clot.
• Blockage of smaller veins (branch veins or BRVO) in the retina often occurs in places where retinal arteries that have been thickened or hardened by atherosclerosis cross over and place pressure on a retinal vein.

Risk factors for retinal vein occlusion include:

• Atherosclerosis
• Diabetes
• High blood pressure (hypertension)
• Other eye conditions, such as glaucoma, macular edema, or vitreous hemorrhage

The risk of these disorders increases with age, therefore retinal vein occlusion most often affects older people.

Blockage of retinal veins may cause other eye problems, including:

• Glaucoma (high pressure in the eye), caused by new, abnormal blood vessels growing in the front part of the eye
• Macular edema, caused by the leakage of fluid in the retina

Symptoms

• Symptoms include sudden blurring or vision loss in all or part of one eye.

Exams and Tests

Tests to evaluate for vein occlusion include:

• Exam of the retina after dilating the pupil

An eye test that uses a special dye and camera to look at blood flow in the retina and choroid.

• Intraocular pressure
• Pupil reflex response
• An eye exam that measures a person's prescription for eyeglasses or contact lenses
• Retinal photography
• Slit lamp examination
• Testing of side vision (visual field examination)
• Visual acuity test to determine the smallest letters you can read on a chart

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Retinitis pigmentosa (RP) is a group of genetic disorders that affect the retina’s ability to respond to light. This inherited disease causes a slow loss of vision, beginning with decreased night vision and loss of peripheral (side) vision

Retinitis pigmentosa causes slow loss of vision. Symptoms begin with decreased night vision and later progress to loss of peripheral (side) vision — creating a “tunnel vision” effect. Some people may also have difficulty identifying colors. The rate of vision change varies in different people depending on the genetic makeup of their disorder.

As night vision decreases, the ability to adjust to darkness becomes more difficult. You may stumble over objects in the dark, find driving at dusk and night difficult and see poorly in dimly lit rooms, such as a movie theater. While your vision during the day may be completely normal, your inability to see in dark conditions is considered “night blindness.”

In some cases, central vision may be affected first, making detail work difficult, such as reading or threading a needle. This may be referred to as macular dystrophy, because the central area of the retina, called the macula, is affected.

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Is a rare form of cancer that rapidly develops from the immature cells of a retina, the light-detecting tissue of the eye. It is the most common malignant cancer of the eye in children, and it is almost exclusively found in young children

The most common and obvious sign of retinoblastoma is an abnormal appearance of the retina as viewed through the pupil, the medical term for which is leukocoria, also known as amaurotic cat's eye reflex.Other signs and symptoms include deterioration of vision, a red and irritated eye with glaucoma, and faltering growth or delayed development. Some children with retinoblastoma can develop a squint,commonly referred to as "cross-eyed" or "wall-eyed" (strabismus). Retinoblastoma presents with advanced disease in developing countries and eye enlargement is a common finding.

Depending on the position of the tumors, they may be visible during a simple eye exam using an ophthalmoscope to look through the pupil. A positive diagnosis is usually made only with an examination under anesthetic (EUA). A white eye reflection is not always a positive indication of retinoblastoma and can be caused by light being reflected badly or by other conditions such as Coats' disease.

The presence of the photographic fault red eye in only one eye and not in the other may be a sign of retinoblastoma. A clearer sign is "white eye" or "cat's eye" (leukocoria).

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Retinopathy of prematurity (ROP) or Terry syndrome, previously known as retrolental fibroplasia (RLF), is a disease of the eye affecting prematurely-born babies generally having received intensive neonatal care, in which oxygen therapy is used on them due to the premature development of their lungs. It is thought to be caused by disorganized growth of retinal blood vessels which may result in scarring and retinal detachment. ROP can be mild and may resolve spontaneously, but it may lead to blindness in serious cases. As such, all preterm babies are at risk for ROP, and very low birth weight is an additional risk factor. Both oxygen toxicity and relative hypoxia can contribute to the development of ROP.Screening is absolutely mandatory.

Retinal Laser-Photocoagulation uses light to create a thermal burn in retinal tissue. When energy from a strong light source is absorbed by the retinal pigment epithelium (RPE) and is converted into thermal energy, coagulation necrosis occurs with denaturation of cellular proteins as temperature rises above 65°C.

Indications

Panretinal photocoagulation (PRP) for neovascular proliferative diseases such as proliferative diabetic retinopathy, sickle cell retinopathy, and venous occlusive diseases

• Treatment of threshold and high-risk prethreshold retinopathy of prematurity
• Closure of retinal microvascular abnormalities such as microaneurysms, telangiectasia and perivascular leakage
• Focal ablation of extrafoveal choroidal neovascular membrane
• Creation of chorioretinal adhesions surrounding retinal breaks and detached areas
• Focal treatment of pigment abnormalities such as leakage from central serous chorioretinopathy
• Treatment of ocular tumors
• Treatment of the ciliary body to decrease aqueous production for glaucoma

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• Subconjunctival hemorrhage, or broken blood vessel on the sclera
• Blepharitis, or inflamed eyelids
• Stye, or a red bump on the eyelid
• Special-effect contact lenses to create a "crazy" red-eye effect
• Red eyes in photos
• Dry allergies
• Contact lenses
• Computer vision syndrome
• Eye injury
• Cornea ulcer
• Uveitis
• Glaucoma
• Cold and flu
• Pregnancy
• Smoking

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Strokes can affect vision in a number of ways, including decreased vision and double vision:

• Decreased vision is caused by damage to the fibers that transmit visual information from the eyes to the brain. This can occur in a variety of locations, since the nerve fibers that transmit vision have a long course from the eyes to the rearmost part of the brain, called the occipital lobe.
• Double vision is caused by damage to nerves responsible for moving the eyes and ensuring that both eyes are aligned (i.e. looking at the same place).

After the optic nerve exits the eyeball from the back of each eye, it travels a short distance before the nasal fibers (the optic nerve fibers on the side of the eye closer to the nose) from each eye cross over to the opposite side (make an "X") as they continue traveling toward the brain. Here is what happens in the eye and brain when we look at an object:

• In the right eye, the nasal fibers (shown in orange in the diagram above), which see the far right part of the visual field, cross over to the left side of the brain, while the temporal fibers (those on the side of the eye closer to the temple) which see the far left part of the visual field, do not cross over (in purple).
• In the left eye, the nasal fibers (in purple), which see the far left part of the visual field, cross over to the right side of the brain, while the temporal fibers (those on the side of the eye closer to the temple) which see the far right part of the visual field, do not cross over (in orange). Therefore a stroke, lesion, or injury at the point where the nasal fibers from each eye cross (where the fibers make an "X", called the optic chiasm), would cause loss of the right visual field in the right eye and loss of the left visual field in the left eye.

• Scleritis is Scleral inflammation may occur in one or both eyes.
• Pain is the hallmark symptom and signs of scleritis include focal or diffuse redness or violaceous discoloration, initial scleral thickening, late scleral thinning, nodules, and necrosis. It may be associated with keratitis, iritis, glaucoma, and exudative retinal detachment.
• Scleritis commonly has an underlying cause, usually an autoimmune disease (rheumatoid arthritis, granulomatosis with polyangiitis, other vasculitic/connective tissue diseases).
• Treatment include corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs),immunosuppressives, and biologics.

Sudden loss of vision

• Some patients describe their symptoms as a gradually descending gray-black curtain or as blurring, fogging, or dimming of vision. Symptoms usually last a few minutes but can persist for hours. Variation in frequency ranges from a single episode to many episodes per day; recurrences may continue for years but more frequently occur over seconds to hours.
• Many different causes of sudden visual loss are recognized; however, the most common reason for painless sudden visual loss is ischemia. Vision loss with positive scotoma may be seen with migraine. Vision loss with a negative scotoma may be seen with amaurosisfugax.
• Other etiologies of sudden visual loss include infection/inflammation, vasculitis, trauma, mechanical dysfunction, and idiopathic causes

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Stargardt disease, or fundus flavimaculatus, is an inherited form of juvenile macular degeneration that causes progressive vision loss usually to the point of legal blindness. Several genes are associated with the disorder. Symptoms, mainly vision loss, typically develop before age 20, and also include wavy vision, blind spots, blurriness, impaired color vision, and difficulty adapting to dim lighting.

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Shadow in vision /letter: A shadow or dark curtain describes when vision is decreased or partially blocked by dark or grey shapes moving across or in the side of the visual field.Shadows are small moving spots that appear in a person’s field of vision, floaters typically occur when tiny pieces of the eye’s gellike vitreous humor break loose within the inner back portion of the eye. While annoying, ordinary floaters are very common and rarely are cause for alarm. The sudden onset of flashing lights, a noticeable increase in the amount of floaters, a shadow in your peripheral vision, or a gray curtain moving across your field of vision could be signs of a detachment of the retina — the nerve layer in the back of the eye that sends images to the brain.

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A brown spot on the eye is an abnormal brown growth on the eye, usually on the conjunctiva or iris,may be associated with:Nevus/Ocular Melanoma. A red or pink spot on the eye is the abnormal appearance of a spot on the eye, often due to blood leakage.(Subconjunctival Hemorrhage)

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A subconjunctival hemorrhage:it's like a bruise of the eye. It usually appears as a single, concentrated spot of red, or many scattered red splotches, on the white of the eye. The redness is blood under the conjunctiva, a clear membrane that covers the white of the eye (called the sclera) and the inner eyelids.Seeing a subconjunctival hemorrhage on your eye can be alarming. Yet it is actually a common minor occurrence. It is almost always harmless and will heal on its own. It does not affect vision and generally does not cause pain. There are usually no sensations or symptoms, other than the appearance of the red spot.

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Swelling around the eye is inflammation that can affect the eyelids and tissues around the eye. May be associated with Cellulitis,Chalazion,EyeAllergies,Retinoblastoma(tumors)

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Stickler syndrome :it is a genetic disorder that affects collagen, the connective tissue of the body. Collagen is a main component of the cornea, the clear, round dome covering the eye's iris and pupil, and the sclera (the white part of the eye). A parent with Stickler syndrome has a 50 percent chance of passing the disorder along to a child. They are often born with severe nearsightedness (high myopia), meaning that they can only see objects very close to them. In addition, some children are born with cataracts, a clouding of the eye’s lens.Children with Stickler syndrome may also develop glaucoma, a disease that damages the optic nerve, or have retinal detachments that can threaten sight.If the child has a cataract in both eyes, it is possible that surgery may be delayed for years, or, depending on their severity, it may never become necessary. In the event that a detached retina occurs, surgery is necessary to re-attach the retina.Glaucoma associated with Stickler syndrome is most commonly treated by medicated eyedrops, although surgery may be needed.In cases of severe nearsightedness (high myopia), vision can often be easily corrected with glasses, contact lenses or sometimes with refractive surgery.

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Crossed eyes (or strabismus) occur when a person’s eyes are not able to align on the same point at the same time, and appear to be misaligned or pointed in different directions.

Symptoms

• Eyes that do not move together
• Unsymmetrical points of reflection in each eye
• Tilting the head to one side
• Inability to gauge depth
• It could be unilateral or bilateral
• Stroke Affecting the Eye
• Subconjunctival Hemorrhage
• Shadown in vision
• Small eye
• Spot on eye

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symptoms may include:

• A lump on the top or bottom eyelid
• Localized swelling of the eyelid
• Localized pain
• Redness
• Tenderness
• Crusting of the eyelid margins
• Burning in the eye
• Droopiness of the eyelid
• Scratchy sensation on the eyeball (itching)
• Blurred vision
• Mucous discharge in the eye
• Irritation of the eye
• Light sensitivity
• Tearing
• Discomfort during blinking
• Sensation of a foreign body in the eye

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In Brief

Crossed eyes (or strabismus) occur when a person’s eyes are not able to align on the same point at the same time, and appear to be misaligned or pointed in different directions.

• Symptoms-Eyes that do not move together
• Unsymmetrical points of reflection in each eye
• Tilting the head to one side
• Inability to gauge depth
• Squinting with only one eye

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Could be due to conjunctivitis-

• Thick yellow discharge that crusts over the eyelashes, especially after sleep
• Green or white discharge from the eye
• Itchy eyes
• Burning eyes
• Blurred vision
• Increased sensitivity to light

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Causes of a swollen eye, including eye infections , trauma, and, most commonly, allergies. Swelling of the eyelids can be a sign of a more serious, potentially sight-threatening health problem, such as orbital cellulitis, Graves' disease and ocular herpes.

Symptoms

• Eye irritation, such as an itchy or scratchy sensation
• Excess tear production, resulting in watering eyes
• Obstructed vision (depending on the extent of the swelling)
• Redness of the eyelid
• Red eyes and inflammation of the conjunctiva
• Eye discharge, or "mattering"
• Eyelid dryness or flaking
• Pain, particularly when swollen eyelids are caused by infection

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Also called microphthalmia, an abnormally small eye, a congenital malformation (birth defect) of the globe. The related term "anophthalmia" means no eye and refers to absence of the globe and ocular tissue from the orbit. Microphthalmia may involve one or both eyes. It may occur in isolation with no associated malformations or it may be part of a multiple congenital malformation syndrome as, for example, the congenital rubella syndrome, the triploidy syndrome (due to the presence of 69 chromosomes), the trisomy 13 syndrome (Patau syndrome, due to an extra chromosome 13), and the Wolf-Hirschorn syndrome (due to deletion of part of the short arm of chromosome 4).

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Trachoma, an eye infection affecting both eyes, is the world’s leading cause of preventable blindness. According to the World Health Organization (WHO), trachoma is responsible for the visual impairment of 2.2 million people, of whom 1.2 million are irreversibly blind. Trachoma is caused by a bacterium called Chlamydia trachomatis.In its early stages, trachoma causes conjunctivitis (pink eye). Early symptoms, which begin to appear within five to 12 days of exposure to the bacterium, can include mild itching and irritation of the eyes and eyelids and a discharge from the eyes. As the infection progresses, it causes eye pain and blurred vision. If the infection is untreated, scarring occurs inside the eyelid. This leads to the eyelashes turning inward toward the eye, a condition called trichiasis. The eyelashes brush and scratch against the cornea, the clear covering at the front of the eye. This continual irritation turns the cornea cloudy and can lead to the development of corneal ulcers and vision loss.

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tired, itching and burning eyes

associated with headaches or with eye problems such as:

• Discomfort
• Double vision
• Significant change in vision
• Causes- Reading
• Writing
• Driving

Exposure to bright light or straining to see in dim light can also cause eye fatigue.

One of the most common causes of eye fatigue is staring for long periods at digital devices such as:

• Computer screens
• Smartphones
• Video games

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Tunnel vision (also known as Kalnienk vision) is the loss of peripheral vision with retention of central vision, resulting in a constricted circular tunnel-like field of vision. Tunnel vision can be caused by:Glaucoma, a disease of the eye. Retinitis pigmentosa, a disease of the eye. Blood loss (hypovolemia),Alcohol consumption. Hallucinogenic drugs, in particular the dissociatives,Extreme fear or distress.

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Trichiasis is a medical term for abnormally positioned eyelashes that grow back toward the eye, touching the cornea or conjunctiva. This can be caused by infection, inflammation, autoimmune conditions, congenital defects, eyelid agenesis and trauma such as burns or eyelid injury. It is the leading cause of infectious blindness in the world. Standard treatment involves removal or destruction of the affected eyelashes with electrology, specialized laser, or surgery.

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Usher syndrome is responsible for the majority of deaf-blindness. The word syndrome means that multiple symptoms occur together, in this case, deafness and blindness. It occurs in roughly 1 person in 23,000 in the United States, 1 in 28,000 in Norway and 1 in 12,500 in Germany. People with Usher syndrome represent roughly one-sixth of people with retinitis pigmentosa. Usher syndrome is inherited in an autosomal recessive pattern. "Recessive" means both parents must contribute an appropriate gene for the syndrome to appear, and "autosomal" means the gene is not carried on one of the sex chromosomes (X or Y), but rather on one of the 22 other pairs. (See the article on human genetics for more details.)The progressive blindness of Usher syndrome results from retinitis pigmentosa. The photoreceptor cells usually start to degenerate from the outer periphery to the center of the retina, including the macula. This syndrome is characterized by hearing loss and a gradual visual impairment.

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Uveitis is the inflammation of the uvea, the pigmented layer that lies between the inner retina and the outer fibrous layer composed of the sclera and cornea. The uvea consists of the middle layer of pigmented vascular structures of the eye and includes the iris, ciliary body, and choroid. Uveitis is an ophthalmic emergency and requires a thorough examination by an optometrist or ophthalmologist and urgent treatment to control the inflammation.

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The main symptom of vitamin A deficiency is vision loss and blindness.

Vision loss often begins as a problem adjusting to seeing in the dark, or night blindness. People with night blindness do not see well in the dark, but are able to see normally if enough light is present. As the vitamin A deficiency worsens, the conjunctiva, the covering on the white of the eye that helps lubricate your eye, dries out, and corneal ulcer appear. The progression of the deficiency eventually leads to vision loss and blindness.

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• Clouding of normally transparent eye structures(Damage to the cornea caused by infections such as herpes keratoconjunctivitis or an infection that follows contact lens overwearing, which results in an opaque corneal scar, vitamin A deficiency (keratomalacia), which causes dry eyes and results in an opaque corneal scar (rare in developed nations),A cataract, which causes loss of clarity of the lens)
• Abnormalities of the retina (the light-sensing structure at the back of the eye)( Detached retina,Diabetesmellitus,Maculardegeneration,Retinitispigmentosa, a blockage of the retinal artery or vein, which may be caused by inflammation of the blood vessel wall (such as that caused by giant cell arteritis), or due to a blood clot that travels to the eye from somewhere else (such as from the carotid artery in the neck), Infection of the retina (such as from Toxoplasma,parasites, or fungi) in people who have AIDS)
• Abnormalities of the nerves that carry visual signals from the eye to the brain (the optic nerve and the visual pathways){ brain tumors, strokes, infections, and multiple sclerosis,Glaucoma,Inflammation of the optic nerve (optic neuritis)
• Eye injury

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Vision Loss, Central : Central vision loss is the loss of detail vision, resulting in having only side vision remaining

Causes

• Age-Related Macular Degeneration (AMD)
• Diabetic Retinopathy
• Macular Edema
• Macular Hole
• Macular Pucker

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Peripheral vision problems mean that you don't have a normal, wide-angle field of vision, even though your central vision may be fine.causes:

• Glaucoma
• Retinitis pigmentosa
• Eye strokes or occlusions
• Detached retina
• Brain damage from stroke, disease or injury
• Neurological damage such as from optic neuritis
• Compressed optic nerve head (papilledema)
• Concussions (head injuries)*

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Watering eye ,also known as epiphora or tearing, is a condition in which there is an overflow of tears onto the face, often without a clear explanation. There are two main causes of watering eyes - blocked tear ducts or excessive production of tears. If a patient's tear ducts are narrowed or blocked their tears will not be able to drain away and will build up in the tear sac. cause of over-production of tears:Some chemicals, such as fumes, and even onions,Infective conjunctivitis,Allergicconjunctivitis,An injury to the eye, such as a scratch or a bit of grit (tiny pebble or piece of dirt),Trichiasis - inward-growing eyelashes, often caused by marginal entropion (the eye lid turns in at the edges towards the eye),Ectropion - this is when the lower eyelid turns outwards

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The most common causes of wavy lines in eyesight include ocular migraine and macular degeneration,. Metamorphopsia is the medical term for this form of vision disturbance, Ocular migraines are transient, painless episodes that involve visual disturbances, such as blind spots, wavy lines, zigzag lines, moving colors and flashing lights.Macular degeneration is a potentially serious, age-related condition that involves the breakdown of the macula, the central portion of the retina.

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Arcus senilis (or arcus seniliscorneae) is a white, grey, or blue opaque ring in the corneal margin (peripheral corneal opacity), or white ring in front of the periphery of the iris.it is quite commonly present in the elderly. It can also appear earlier in life as a result of hypercholesterolemia.

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A white or cloudy spot on the eye is an abnormal appearance either on the eye or seen through the pupil causes:CornealUlcer,Retinoblastoma,Uveitis.

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Yellowing of the eyes occurs if you have jaundice. Jaundice occurs when the oxygen-carrying components in the blood, called hemoglobin, break down into bilirubin and your body doesn’t clear the bilirubin.

Yellow spot on eye:A pinguecula (above) is a yellowish patch or bump on the conjunctiva, near the cornea. It most often appears on the side of the eye closest to the nose. It is a change in the normal tissue that results in a deposit of protein, fat and/or calcium. It is similar to a callus on the skin.

A pterygium (also known as surfer's eye or farmer's eye) is a triangular-shaped growth of fleshy tissue on the white of the eye that eventually extends over the cornea. This growth may remain small or grow large enough to interfere with vision. A pterygium can often develop from a pinguecula.

YAG lasers :Nd:YAG (neodymium-doped yttrium aluminium garnet; Nd:Y3Al5O12) is a crystal that is used as a lasing medium for solid-state lasers. The dopant, triply ionized neodymium, Nd(III), typically replaces a small fraction (1%) of the yttrium ions in the host crystal structure of the yttrium aluminium garnet (YAG), They are used in ophthalmology to correct posterior capsular opacification, a condition that may occur after cataract surgery, and for peripheral iridotomy in patients with acute angle-closure glaucoma, where it has superseded surgical iridectomy. Frequency-doubledNd:YAG lasers (wavelength 532 nm) are used for pan-retinal photocoagulation in patients with diabetic retinopathy. In certain cases these lasers are also used to treat eye floaters.

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