Eye Care > Refractive Surgery > Glossary

Glossary

Astigmatis

With astigmatism, light rays form a line on the retina due to an irregularity in the curve of the cornea. The result is blurred vision at all distances.

Cornea

The clear window at the front of the eye that provides most of the focusing power.

Farsightedness (hyperopia)

With farsightedness, the eye is too short to focus light on the retina. This makes it easy to focus on distant objects, but not on images that are close.

Lens

The lens helps focus light on the retina.

Nearsightedness (myopia) 

With nearsightedness, light rays pass through the cornea and lens and converge in front of the retina, not on the retina. This makes close objects appear clear, but objects in the distance blurry.

Presbyopia

The loss of the eye's ability to change focus to see near objects.

Pupil

The opening at the center of the eye that allows light in varying amounts into the eye.

Refraction

A test to help determine the best vision correction option for you, whether you are nearsighted, farsighted or have astigmatism.

Retina

The light sensitive nerve tissue, located in the back of your eye, that sends visual images to your brain.

Visual acuity

The ability to distinguish details and shapes of objects.