hard lens

The eyes, on either side of the head, each contain a hard lens.

Hard lenses are generally well tolerated and are relatively easy to care for.

The bulb is fragile so some manufacturers offer protective covers and hard lenses.

They take less time to get used to than hard lenses, but they are less durable.

Some people cannot tolerate hard lenses.

Like the original hard lenses, these require a daily cleaning and disinfecting process that if not properly followed can increase the risk of mishaps.

Hard lenses, soft lenses and everything in between are available, including disposable, bifocal and colored lenses.

Rigid gas-permeable (RGP) lenses are more comfortable than conventional hard lenses.

Deposits on the lenses, which may make the lenses less comfortable and increase the risk of infection (deposits are rare with hard lenses).

PMMA hard lenses were very durable, and were commonly worn for 5 to 10 years, but had other drawbacks.

This in turn stimulated interest in the development of improved hard lens materials to replace PMMA.

Soft contact lenses tend to be more comfortable than hard lenses, but hard lenses usually provide sharper vision.

As well as simple combination cleaning and disinfectant solutions for both soft and hard lenses, pH neutral solutions are available for people with particularly sensitive eyes.

Almost without exception that investment is directed at bifocals and new materials that will combine the good vision correction of hard lenses with the comfort of soft lenses.

Bausch & Lomb also recently introduced an extended-wear rigid gas permeable lens that, unlike normal hard lenses, can be worn for several days because of their superior permeability.

A Cafeteria of Contacts The original hard lenses that had to be removed nightly and took weeks to get used to (many people never could) have yielded to more comfortable and convenient alternatives.

Conventional hard lenses (PMMA) are made of a stiff plastic (polymethyl methacrylate, or PMMA), which does not mold to the shape of the eye.

I accustomed my pupils to the tiny hard lenses - building up their resistance fastidiously for an extra hour per day - then lost one down the sink and the other down the Holborn Public Baths.

Now the company is ready to introduce a hybrid lens, already in use in Europe, that combines the superior vision correction of a hard lens in the center of the lens with the comfort of a soft lens in the perimeter.