Why is it called a hard lens?

Simply because it is hard and is not flexible. Though it has a certain degree of 'give' in it, it does not mould itself to the eye.

What are the types of hard lenses?

(a) Corneal contact lenses which fit on the clear part of the eye or the cornea.

(b) Scleral or haptic lenses which cover in addition to the cornea, part of the white of the eye. Haptic lenses are rarely fitted.

What are the types of corneal lenses?

(a) A large lens of 10-12 mm in diameter, termed a corneal lens.

(b) A small lens of less than 9.5 mm termed a microcorneal lens. This is the most common type of lens fitted to-day.

What are they made of?

These are made of a special quality of polymethmethacrylate, a special plastic which has a good resistance to scratches, low tendency to warp and can be polished to a high brilliance. Contact lenses are very thin (almost one 200th of an inch in thickness) and must be handled with care.

How do I know if hard contact lenses will suit me?

The answer is usually given by a trial wear of lenses at the doctor's clinic. Quite often the doctor can tell after examination whether hard lenses will suit you or recommend an alternative if they do not.

Can a contact lens slip behind the eye?

No. The space between the lids and the eye is a securely closed space. If the lenses are displaced from the cornea to the white of the eye, they can be easily recentred by methods taught to you by the doctor.

Bianca Cohen

Copyrighted material; do not reprint without permission.

 

View all articles by Bianca Cohen