Definitions

Some of the common terms and conditions used in Optometry.

Emmetropia is normal sightedness. The light enters the eye through the Cornea and Pupil. The lens changes shape to focus light onto the retina correctly. The retina detects the light and passes a signal to the brain along the optic nerve.

Myopia or short-sightedness occurs when the lens naturally focuses light in front of the retina. The lens may change shape to focus the light onto the retina for near objects, but cannot focus the light from far away objects correctly.

Hyperopia or long-sightedness occurs when the lens naturally focuses light behind the retina. The lens may change shape to focus the light onto the retina for far objects, but cannot focus the light from near objects correctly.

Presbyopia is when the muscles controlling the lens cannot correctly focus the light onto the retina. Most people over the age of 45 have this problem. People with presbyopia may need glasses for reading and close work.

Astigmatism is when the cornea is slightly misshaped. This can cause slight distortion or blurring in the vision.

Amblyopic are ‘lazy eyes’. This is usually due to a crossed eye or higher prescription that was not treated when a child.