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vision

(Encyclopedia)CE5 Optic nerve vision, physiological sense of sight by which the form, color, size, movements, and distance of objects are perceived. Defects of vision include astigmatism, color blindness, far...

macular degeneration

(Encyclopedia)macular degeneration, eye disorder causing loss of central vision. The affected area, the macula, lies at the back of the retina and is the part that produces the sharpest vision. The most serious vis...

sight

(Encyclopedia)sight: see vision.

optic nerve

(Encyclopedia)optic nerve: see vision.

visual purple

(Encyclopedia)visual purple: see vision.

Young-Helmholtz theory

(Encyclopedia)Young-Helmholtz theory: see vision. ...

retina

(Encyclopedia)retina: see vision; eye. ...

glaucoma

(Encyclopedia)glaucoma glôkōˈmə [key], ocular disorder characterized by pressure within the eyeball caused by an excessive amount of aqueous humor (the fluid substance filling the eyeball). This causes pressure...

farsightedness

(Encyclopedia)farsightedness or hyperopia, condition in which far objects can be seen easily but there is difficulty in near vision. It is caused by a defect of refraction in which the image is focused behind the r...

Langland, William

(Encyclopedia)Langland, William, c.1332–c.1400, putative author of Piers Plowman. He was born probably at Ledbury near the Welsh marshes and may have gone to school at Great Malvern Priory. Although he took minor...