Cataract:
A clouding in the lens making it difficult to see.

Glaucoma:
A disease process that damages the optic nerve and leads to blindness.

Diabetic Retinopathy:
A result of diabetes mellitus causing retinal bleeding which may lead to blindness.

Dry Eye:
Insufficient moisture in the eye causing excessive tearing and discomfort.

Myopia:
Nearsightedness.

Hyperopia:
Farsightedness.

Astigmatism:
Blurry vision at both distance and near.

Amblyopia:
Medical term for eye with poor visual acuity with no apparent pathologic condition.

Presbyopia:
Poor vision at near, due to loss of accommodation from aging.