Floater: A blurry spot that seems to drift in front of the eyes but does not block vision. The blur is the result of debris from the vitreous of the eye casting a shadow on the retina. The spot is the image formed by a deposit of protein drifting about in the vitreous, the clear jelly-like substance that fills the middle of the eye. Floaters are often described by patients as spots, strands, or little flies. Floaters are usually benign (not serious). They can, however, occasionally result from a separation of the vitreous gel from the retina. This condition is called a posterior vitreous detachment (PVD). Although a PVD occurs commonly, there are no retinal tears associated with the condition most of the time.No treatments...

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Tags: Eye, Vision

The visual acuity score compares your distance vision with that of people who have normal vision, using an eye chart. Each eye's score is expressed as two numbers, such as 20/20 (6/6) or 20/100 (6/30). The first number is the distance you stand from the chart, usually 20 ft (6 m) when using a typical wall chart. The second number is the distance from which people with normal eyesight can read the same line on the eye chart.  20/20 (6/6) vision is considered normal. A person with 20/20 vision can see at 20 ft (6 m) what people with normal vision can see at this distance. When the second number is smaller than the first number, the person's vision is better than normal. For instance, a person...

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Tags: refraction, Vision

Refraction Refraction is a test that measures the eye's need for a corrective lens (refractive error). For this test, you will be asked to describe the effects of looking at an eye chart through various corrective lenses. Your health professional may use eyedrops to widen (dilate) your pupils before you start this test. The eyedrops take about 15 to 20 minutes to dilate the pupil fully. Using a retinoscope, your health professional may shine light into your eyes. A series of trial lenses will be placed in front of your eyes and adjusted until the light rays are properly focused on your retina. Testing one eye at a time, the health professional will ask you to compare the effects of...

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Tags: refraction, Vision

How It Is Done Visual acuity testing Visual acuity tests are used to evaluate eyesight. Several types of visual acuity tests may be used. The Snellen test checks your ability to see at distances. It uses a wall chart that has several rows of letters. The letters on the top row are the largest; those on the bottom row are the smallest. You will stand or sit 20 ft (6 m) from the chart and be asked to cover one eye and then read the smallest row of letters you can see on the chart. If you are unable to cover your eye, an eye patch will be placed over your eye. Each eye is tested separately. You may be given a different chart or asked to read a row...

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Vision tests check many different functions of the eye. The tests measure your ability to see details at near and far distances, check for gaps or defects in your field of vision, and evaluate your ability to see different colors. Visual acuity tests are the most common tests used to evaluate eyesight. They measure the eye's ability to see details at near and far distances. The tests usually involve reading letters or looking at symbols of different sizes on an eye chart. Usually, each eye is tested by itself. And then both eyes may be tested together, with and without corrective lenses (if you wear them). Several types of visual acuity tests may be used. Refraction is a test ...

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Tags: Refractive error, Vision