Search results
Results From The WOW.Com Content Network
In the most familiar acuity test, a Snellen chart is placed at a standard distance: 6 metres. At this distance, the symbols on the line representing "normal" acuity subtend an angle of five minutes of arc, and the thickness of the lines and of the spaces between the lines subtends one minute of arc. This line, designated 6/6 (or 20/20), is the ...
Ophthalmology ( / ˌɒfθælˈmɒlədʒi /, OFF-thal-MOL-ə-jee) [ 1] is a clinical and surgical specialty within medicine that deals with the diagnosis and treatment of eye disorders. [ 2] A former term is oculism . An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. [ 3]
Distance PD is the separation between the visual axes of the eyes in their primary position, as the subject fixates on an infinitely distant object. [ 2] Near PD is the separation between the visual axes of the eyes, at the plane of the spectacle lenses, as the subject fixates on a near object at the intended working distance. [ 3]
A good's price elasticity of demand ( , PED) is a measure of how sensitive the quantity demanded is to its price. When the price rises, quantity demanded falls for almost any good ( law of demand ), but it falls more for some than for others. The price elasticity gives the percentage change in quantity demanded when there is a one percent ...
The price elasticity of supply ( PES or Es) is a measure used in economics to show the responsiveness, or elasticity, of the quantity supplied of a good or service to a change in its price. Price elasticity of supply, in application, is the percentage change of the quantity supplied resulting from a 1% change in price.
An eye chart is a chart used to measure visual acuity comprising lines of optotypes in ranges of sizes. Optotypes are the letters or symbols shown on an eye chart. [ 1 ] Eye charts are often used by health care professionals, such as optometrists , physicians and nurses , to screen persons for vision impairment .
The term "optometry" comes from the Greek words ὄψις (opsis; "view") and μέτρον (metron; "something used to measure", "measure", "rule").The word entered the language when the instrument for measuring vision was called an optometer, (before the terms phoropter or refractor were used).
The cup-to-disc ratio (often notated CDR) is a measurement used in ophthalmology and optometry to assess the progression of glaucoma. The optic disc is the anatomical location of the eye's "blind spot", the area where the optic nerve leave and blood vessels enter the retina. The optic disc can be flat or it can have a certain amount of normal ...