Accommodation, Accommodation is the process by which the eye increases optical power to maintain a clear image (focus) on an object as it draws near the eye.

Achromatopsia, Achromatopsia (ACHM) is the inability to see color. Although the term may refer to acquired disorders such as color agnosia and cerebral achromatopsia, it typically refers to an autosomal recessive congenital color vision disorder, also called rod monochromacy and total congenital color blindness.

Age Related Macular Degeneration, Age-related macular degeneration begins with characteristic yellow deposits in the macula (central area of the retina which provides detailed central vision, called fovea) called drusen between the retinal pigment epithelium and the underlying choroid.

Amblyopia, A disorder of the visual system that is characterized by poor or indistinct vision in an eye that is otherwise physically normal, or out of proportion to associated structural abnormalities. It has been estimated to affect 1–5% of the population.

Anterior Chamber of the eyeball, The front section of the eye's interior where aqueous humor flows in and out providing nourishment to the eye and surrounding tissues.

Aphakia, The absence of the lens of the eye, due to surgical removal, a perforating wound or ulcer, or congenital anomaly

Aqueous Humor, The aqueous humour is a thick watery substance that fills the space between the lens and the cornea.

Asthenopia, Asthenopia or eye strain is an ophthalmological condition that manifests itself through nonspecific symptoms such as fatigue, red eyes, eye strain, pain in or around the eyes, blurred vision, headache and occasional double vision. Symptoms often occur after reading, computer work, or other activities that involve tedious visual tasks.

Astigmatism, Astigmatism is when an optical system has different foci for rays that propagate in two perpendicular planes.