Visual acuity test
This test measures how well you see at various distances. It is the familiar eye chart test.
The eye chart itself — the usual one is called Snellen’s chart — is imprinted with block letters that line-by-line decrease in size, corresponding to the distance at which that line of letters is normally visible.
The letters on Snellen’s chart are, not surprisingly, called Snellen’s test type. Each block letter is quite scientific in design (so that at the appropriate distance the letter subtends a visual angle of 5 degrees and each component part subtends an angle of 1 minute).
The chart and the letters are named for a 19th-century Dutch ophthalmologist Hermann Snellen (1834-1908) who came up with them as a test of visual acuity. Visual acuity refers to the clarity or clearness of the vision, a measure of how well a person sees. The word “acuity” comes from the Latin “acuitas” = sharpness.
Read Also:
- Visual contrast sensitivity
The ability to perceive differences between an object and its background.
- Visual evoked response
VER. A type of electrophysiologic retinal testing done to evaluate the retina and optic nerve by measuring the electrical potential resulting from a visual stimulus.
- Visual field
Hydroxychloroquine is classified as an anti-malarial drug. It is similar to chloroquine (Aralen) and is useful in treating several forms of malaria as well as lupus erythematosus and rheumatoid arthritis. Its mechanism of action is unknown. Malarial parasites invade human red blood cells. Hydroxychloroquine may prevent malarial parasites from breaking down (metabolizing) hemoglobin in human […]
- Visual field
The entire area that can be seen when the eye is directed forward, including that which is seen with peripheral vision. The visual field can be tested to measure the extent and distribution of the field of vision. The test may be done by a number of methods including what are termed confrontation, tangent screen […]
- Visual field test
Plaquenil), can also affect the visual field.