glossary

Short-sightedness, requiring a concave lens to focus the vision. Near-sightedness, an eye that is too powerful or too long. The image forms in front of the retina; a person with myopia thus sees badly in far vision but well in near vision. A Refractive Error in which the eye over-focuses light. Rays of light traveling from a distant object are brought to focus in front of the retina. Requires a minus (concave) lens to correct.

A device that used to determine degree of red or green color vision deficit. A dial on the anomaloscope is adjusted until the viewer (patient) believes that the green-red balance is appropriate compared with a standard yellow light whose intensity can also be varied. When a person with normal color vision views the “match” made by a patient with abnormal color vision, a deficit in either red or green color vision is readily apparent.

The eye?s lens consists of tightly packed layers of transparent protein fibres contained within an elastic capsule. During cataract surgery, the layers of lens fibres are removed, but the posterior part of the lens capsule and its supporting zonular fibres are retained to act as a support for the lens implant.