CONTACT LENSES

Contact lenses are thin, curved plastic disks designed to cover the cornea, the clear front covering of the eye. Contacts provide a safe and effective way to correct vision when used with care and proper supervision. They can offer a good alternative to eyeglasses, depending on your eyes and your lifestyle.

History
Leonardo da Vinci had proposed the idea of applying a corrective lens directly to the surface of the eye as early as 1508, and similar concepts surfaced from René Descartes in 1636, but it was not until 1887 that the German physiologist Adolf Eugen Fick constructed the first successful contact lens.

Why do people choose contact lenses instead of spectacles?
People wear contact lenses for various reasons.
Contact lenses typically provide better vision than spectacles for some visual conditions such as severe short-sightedness [myopia], long-sightedness [hyperopia], astigmatism, corneal distortion, or after cataract removal [aphakia].
Some people like the wider field of view provided by contact lenses, as side vision [peripheral vision] is often blocked, obscured or limited by spectacle frames. Contact lenses do not fog up with changes in temperature - or from perspiration - and they are unaffected by rain.
Many people choose contact lenses because they think glasses make them look less attractive or they find spectacles annoying. Sports players and people involved in vigorous activities often find contact lenses more convenient than spectacles, especially for water sports and contact sports. Priests, psychologists and many others also find that contact lenses avoid the barrier effect that spectacles may cause, thus leading to more direct eye-contact.

Types of contact lenses
Soft contact lenses are lenses made of hydrophilic (water-loving) plastics that absorb liquids. When these materials soak up liquids, they become soft and mold to fit the eyeball. Soft lenses can correct many visual problems. They are quite different from gas permeable lenses. Types of soft contact lenses.
a)Daily-wear soft lenses are the most comfortable, and your eyes will adjust to wearing them in less time than with hard contact lenses. Soft lenses may be worn during vigorous physical activities and playing sports with less likelihood that the lenses will slip out of place. Daily-wear lenses must be removed, cleaned and stored every day.
b)Disposable contact lenses
Disposable contact lenses are lenses which are designed to be replaced on a regular basis, usually either daily, bi-weekly or monthly. The more often a lens is replaced, the less the lens will become deposited with proteins and oils. Many of the problems that contact lens wearers experienced when contact lenses were replaced on an annual or two yearly basis are seldom seen nowadays. Disposable contact lenses are therefore a healthier alternative. Daily disposable contact lenses are a great option for people who only want to wear their contact lenses a few times per week, for example, for sport. They also remove the need for cleaning, since they are inserted in the morning (or before you play sport) and then thrown away afterward, offering exceptional convenience and good value for money. Lenses, which are replaced two-weekly or monthly, are good value if you want to wear lenses everyday.
c)Leave-in (extended wear) contact lenses
Leave-in (extended wear) contact lenses are designed to be worn continuously for 30 days and nights and then replaced with a new contact lens. They offer the ultimate in convenience, since they usually don't need removing or mechanically cleaning. Other advantages include being able to see without struggling to find your glasses if you get up in the night, or not having to worry about removing lenses with dirty hands if you go camping. You also won't need to remember to carry bottles of solutions around with you if you go out with friends and end up staying out the night!

Toric Contact Lenses
Have you been told you can't wear soft contact lenses because you have astigmatism?
You have the option!
Toric contact lenses are made from the same materials as regular ("spherical") contact lenses, Toric lenses have two powers in them, created with curvatures at different angles (one for astigmatism, the other for either myopia or hyperopia). There's also a mechanism to keep the contact lens relatively stable on the eye when you blink or look around. To provide crisp vision, toric contact lenses cannot rotate on your eye.

Gas permeable contact lenses
Gas permeable contact lenses are usually used for the correction of moderate levels of astigmatism. They provide excellent clarity of vision, especially in cases where the astigmatism is irregular (such as with keratoconus). They require a longer period of adaptation than soft lenses. Gas permeable contact lenses offer excellent long-term corneal health since they allow almost as much oxygen to pass through to the cornea as without a lens on the eye.

Many of the problems associated with the reduced oxygen flow through the old-style "hard lenses" are seldom seen nowadays due to the developments in these modern gas permeable materials.

PROSTHETIC CONTACT LENS

It is used in patients with corneal disfigurations, corneal scarring and decentered pupil

Before	After

Some handy tips for safe, comfortable contact lens wear :