Junior Blind of America

We would like to help you learn about some vision-related terms.

Acuity = keenness of perception; sharpness of vision

Amblyopia = diminished sight in one eye (also called Lazy Eye)

Cataract = the clouding of the lens of the eye, which is normally clear; light can no longer pass through the lens easily and vision becomes hazy or blurred; current treatment is the surgical removal of the lens and replacement with a man-made lens, which is safe and successful

Cortical visual impairment = a condition that indicates that the visual systems of the brain do not consistently understand or interpret what the eyes see

Diabetic retinopathy = an eye disorder that is caused by diabetes that usually appears in stages and can lead to blindness; a complication of diabetes caused by damage to blood vessels in the retina

Farsightedness = able to see objects in the distance more clearly than nearby objects

Functional blindness = no useful vision

Glaucoma = the second leading cause of blindness in the United States; a disease where pressure within the eye is so high that it can damage the optic nerve and lead to vision loss; it affects side vision long before central vision is affected

Legal blindness = a central vision acuity for distance of 20/200 or poorer in the better eye with correction; or a field of vision no greater than 20 degrees in widest diameter

Low vision = vision that cannot be further improved by corrective lenses or medical or surgical intervention, although low vision rehabilitation may help someone to use his/her remaining sight more effectively

Macula = the specialized part of the retina responsible for sharp central vision (the ability to see detail)

Macular degeneration = the leading cause of blindness for people over the age of 50; and eye disease that results from damage to the macula

Nearsightedness = able to see objects nearby more clearly than distant objects

Optic nerve atrophy = the degeneration of the part of the eye that carries stimuli from the rods (the part of the retina that allows one to see in low light) and cones (the part of the retina that allows one to see color) to the brain

Optic nerve hypoplasia = underdevelopment of the optic nerve during pregnancy

Retina = the sensory membrane that lines the eye, receives the image formed by the lens, is the immediate instrument of vision, and is connected with the brain by the optic nerve

Retinitis pigmentosa (RP) = condition characterized by the progressive loss of peripheral vision, usually beginning with night blindness

Retinopathy of prematurity = an eye disorder affecting premature infants; ROP affects immature blood vessels of the retina

Severe vision impairment = inability to read ordinary newsprint with the best correction (glasses or contact lenses)

Strabismus = eye misalignment or eyes that do not move normally, caused by an imbalance of the muscles that move the eyeball

Visual impairment = trouble seeing with one or both eyes when wearing glasses or contact lenses