Eyecare Glossary

Photochromic lenses, also called transition lenses, are eyeglass lenses that darken in response to UV light exposure. They contain special molecules that undergo a chemical reaction when exposed to UV radiation, causing the lenses to darken. This darkening provides protection against bright sunlight and reduces the intensity of glare. When the UV light diminishes, such as when indoors, the lenses gradually return to their clear state.

A form of long-sightedness brought on by ageing and the lens of the eye losing its flexibility, which often happens in middle and elderly life. The terms "multifocal," "progressive," "bifocal," or "presbyopia" are frequently used to describe contact lenses used to correct presbyopia.

The iris's central opening, through which light can enter to the rear of the eye.