Contact lens is a pair of small plastic discs that are placed over the cornea and help in correction of vision, providing comfort to the eye, as a bandage or for cosmetic purposes i.e. to change the colour of the eye. Various types of contact lenses are now available.
Types of contact lenses
Rigid Gas Permeable (RGP) :
These lenses are semi-rigid lenses made usually from acrylate and fluorosilicon, a plastic which allows oxygen to enter the eye. They are durable, provide good clarity of vision and have least maintainance. These lenses can be prescribed for all types of vision correction including high astigmatism, post corneal transplant and refractive surgery (RK, PRK & LASIK). In a limited number of cases, these lenses may be prescribed for myopia control.
Soft lenses are made from water-absorbing plastics, which make them pliable and membrane like for maximum comfort. They are ideal for myopes especially athletes and sportsmen as they do not get easily dislodged from the eye.
With modern manufacturing techniques, soft lenses can correct different types of refractive errors. Soft lenses are available in toric (to correct astigmatism), bifocal, weekly disposable, monthly disposable, daily disposable, extended wear lenses. Cosmetic lenses are also available to cover corneal scars, as well as to change the colour of one’s eyes.
Irrespective of the type, all lenses accumulate deposits from the secretions of the eye and the environment. Therefore proper care and hygiene along with changing the lens solution everyday is vital. Scleral contact lenses :
Scleral lenses are large diameter lenses which form a fluid layer between the cornea and the lens. They are helpful in cases of ocular surface disorders like Stevens Johnson syndrome in improving visual acuity and providing comfort to the eye.