Search results
Results From The WOW.Com Content Network
While the macula is preserved there is some loss of pigmentation around it. Retinitis pigmentosa ( RP) is a genetic disorder of the eyes that causes loss of vision. [ 1] Symptoms include trouble seeing at night and decreasing peripheral vision (side and upper or lower visual field). [ 1] As peripheral vision worsens, people may experience ...
Keratoconus. Keratoconus ( KC) is a disorder of the eye that results in progressive thinning of the cornea. [ 3] This may result in blurry vision, double vision, nearsightedness, irregular astigmatism, [ 4] and light sensitivity leading to poor quality-of-life. [ 3][ 5] Usually both eyes are affected. [ 3] In more severe cases a scarring or a ...
In normal use, a much smaller section of the lens is used, so that the distortion is much smaller. Progressive lenses are corrective lenses used in eyeglasses to correct presbyopia and other disorders of accommodation. They are characterised by a gradient of increasing lens power, added to the wearer's correction for the other refractive errors.
A distant object is defined as an object located beyond 6 meters (20 feet) from the eye. When an object is located close to the eye, the rays of light from this object no longer approach the eye parallel to each other. Consequently, the eye must increase its refractive power to bring those rays of light together on the retina.
Adaptation (eye) In visual physiology, adaptation is the ability of the retina of the eye to adjust to various levels of light. Natural night vision, or scotopic vision, is the ability to see under low-light conditions. In humans, rod cells are exclusively responsible for night vision as cone cells are only able to function at higher ...
Photokeratitis or ultraviolet keratitis is a painful eye condition caused by exposure of insufficiently protected eyes to the ultraviolet (UV) rays from either natural (e.g. intense direct or reflected sunlight) or artificial (e.g. the electric arc during welding) sources. Photokeratitis is akin to a sunburn of the cornea and conjunctiva.
The early writers discussed here treated vision more as a geometrical than as a physical, physiological, or psychological problem. The first known author of a treatise on geometrical optics was the geometer Euclid (c. 325 BC–265 BC). Euclid began his study of optics as he began his study of geometry, with a set of self-evident axioms.
Diabetic retinopathy (also known as diabetic eye disease), is a medical condition in which damage occurs to the retina due to diabetes. It is a leading cause of blindness in developed countries. Diabetic retinopathy affects up to 80 percent of those who have had both type 1 and type 2 diabetes for 20 years or more.