SOFT CONTACT LENSES

Despite continual improvements in hard contact lens designs throughout the 1950’s and 1960’s, these lenses were generally uncomfortable for most people to wear. In the late 1950’s the Czechoslovakian chemist Otto Wichterle and his assistant Dr. Drahslov Lim began experimenting in order to create a contact lens that could be made more comfortable, using a soft water absorbing plastic called hydroxyethyl methacrylate (HEMA). This led to the launch of the first soft hydroxyl lenses in some countries in the 1960’s and the first approval of the ‘Soflens’ material by the U.S. FDA in 1971. Soft lens contact lenses were first sold commercially by Bausch & Lomb in 1971 in the U.S. Today about 90% of contact lenses used in the U.S. are soft lenses.

WHAT ARE SOFT CONTACT LENSES?

Soft contact lenses consist of hydrophilic plastic capable of liquid absorption and when they absorb liquids, they become soft and moist and can easily be molded to the eyeball comfortably. Soft lenses can rectify various vision problems and are quite different from gas permeable (RPG) hard lenses. Soft contact lenses are used to correct near sightedness, far sightedness and some forms of astigmatism, which involves the uneven curving of the corneal surface in front of the eye.

TYPES OF SOFT CONTACT LENSES

Daily wear contact lenses are those, which are not to be used overnight and must be cleaned and removed nightly. Also they can be made thick or thin as per individual requirements. In 1999, there was an important discovery of the first silicone hydrogels, which amalgamated the benefits of the high oxygen permeability with the comfort and performance of traditional hydrogels and the newer type of soft lenses were launched for extended (overnight) use. Extended wear contact lenses are usually very thin containing a lot of water allowing oxygen to reach the eyeball even if worn for a long time sometimes even up to 6 consecutive days and nights of wear. However, the downside is that they have greater chances of causing corneal infections than daily wear soft contacts. Disposable contact lenses are those that can be used for a set period of time be it a month, a week or a day and after the lapse of the time period they must be discarded. They must be cleaned every night unless they are of the extended wear disposable variety. The advantages of this type of soft lenses are that they have less chances of causing infection and need less cleaning than regu