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

Before touching the contact lens or one's eyes, it is important to thoroughly wash and rinse hands with a soap that does not contain moisturizers or allergens such as fragrences. The soap should not be antibacterial due to risk of improper hand washing and the possibility of destroying the natural bacteria found on the eye. These bacteria keep pathogenic bacteria from colonizing the cornea. The technique for removing or inserting a contact lens varies slightly depending upon whether the lens is soft or rigid.In all cases, the insertion and removal of lenses requires some training and practice on the part of the user, in part to overcome the instinctive hesitation against actually touching...

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Tags: Contact lens

Caring for Your Contact LensesFollow these guidelines for good care to extend the life of your contact lenses, and protect the safety and health of your eyes.Always wash your hands with warm water and soap before handling your contact lenses or before touching your eyes. Any residue from lotions, soaps, or chemicals may stick to the contact lens, causing pain, irritation, or blurred vision when they are in your eyes. Dry your hands with a clean towel. Wear your contact lenses as prescribed. Your eye doctor will recommend a wearing schedule specific to the type of contact lens you have selected. Only wear your contact lenses for the time recommended. Clean and store your contact lenses as prescribed (in a clean case in fresh solution). Different...

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Tags: Contact lens

A contact lens (also known simply as contacts for a pair) is a corrective, cosmetic, or therapeutic lens usually placed on the cornea of the eye. Types of contact lenses: Contact lenses are classified in many different manners: CORRECTIVE COSMETIC THERAPEUTIC MATERIAL:The first contact lenses were made of glass, which caused eye irritation, and were not wearable for extended periods of time. But when William Feinbloom introduced lenses made from polymethyl methacrylate (PMMA or Perspex/Plexiglass), contact lenses became much more convenient. These PMMA lenses are commonly referred to as "hard" lenses (this term is not used for other types of contact lens).  In 1998, 'silicone hydrogels' became...

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Tags: Contact lens

LASIK Eye SurgeryLaser in-situ keratomileusis, or LASIK, is a popular surgery used to correct vision in people who are nearsighted, farsighted, or have astigmatism.All laser vision correction surgeries work by reshaping the cornea, or clear front part of the eye, so that light traveling through it is properly focused onto the retina located in the back of the eye. LASIK is one of a number of different surgical techniques used to reshape the cornea.What Are the Advantages of LASIK Eye Surgery?LASIK has many benefits, including:It works! It corrects vision. Around 80% of patients will have their desired vision after LASIK. An enhancement can further increase this number. LASIK is associated with very little pain. Vision is corrected...

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Tags: LASIK, Surgery

What is color blindness?Color blindness means you have trouble seeing red, green, or blue or a mix of these colors. It’s rare that a person sees no color at all.Color blindness is also called a color vision problem. A color vision problem can change your life. It makes it harder to learn and read, and you may not be able to have certain careers. But children and adults with color vision problems can learn to make up for their problems seeing color. What causes color blindness?Most color vision problems are inherited (genetic) and are present at birth.People usually have three types of cone cells in the eye. Each type senses either red, green, or blue light. You see color when your cone cells sense different amounts of these three basic...

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Tags: Color blindness

What Is a Stye?A stye is a pimple or abscess that forms in either the upper or lower eyelid. The medical term for stye is hordeolum (pronounced HOR-dee-oh-lumm) and it is an infection caused by bacteria that normally live on the surface of the eyelid skin without causing disease. Some of these germs get trapped along with dead skin cells inside crypts along the eyelid margin. Styes are usually superficial and plainly visible. Occasionally they can reside deeper within the eyelid.An external stye starts as a pimple next to an eyelash. It turns into a red, painful swelling that may last several days before it bursts and then heals. Some external styes are short-lived and self-limiting while others may require the care of your eye doctor.An...

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Tags: Stye