OverviewAn eye exam involves a series of tests to evaluate your vision and check for eye diseases. Your eye doctor is likely to use various instruments, shine bright lights at your eyes and request that you look through an array of lenses. Each test during an eye exam evaluates a different aspect of your vision or eye health. Show
Why it's doneAn eye exam helps detect eye problems at their earliest stage — when they're most treatable. Regular eye exams give your eye care professional a chance to help you correct or adapt to vision changes and provide you with tips on caring for your eyes. And an eye exam might provide clues to your overall health. When to have an eye examSeveral factors can determine how frequently you need an eye exam, including your age, health and risk of developing eye problems. General guidelines are as follows: Children 3 years and youngerYour child's pediatrician will likely check your child's eyes for healthy eye development and look for the most common childhood eye problems — lazy eye, cross-eyes or misaligned eyes. A more comprehensive eye exam between the ages of 3 and 5 will look for problems with vision and eye alignment. School-age children and adolescentsHave your child's vision checked before he or she enters kindergarten. Your child's doctor can recommend how frequent eye exams should be after that. AdultsIn general, if you are healthy and you have no symptoms of vision problems, the American Academy of Ophthalmology recommends having a complete eye exam at age 40, when some vision changes and eye diseases are likely to start. Based on the results of your screening, your eye doctor can recommend how often you should have future eye exams. If you're 60 or older, have your eyes checked every year or two. Have your eyes checked more often if you:
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How you prepareThere are three types of eye specialists. Which specialist you choose might be a matter of preference or will depend on the nature of your eye problem.
Bring your prescription eyewearIf you wear contact lenses or glasses, bring them to your appointment. Your eye doctor will want to make sure your prescription is the best one for you. Other precautionsBring sunglasses to wear after your eye exam. If your eyes are dilated during your exam, sunlight or other bright lights can cause discomfort or blurred vision. Also, consider having someone else drive you home. What you can expectBefore the examIf you're seeing a new eye doctor or if you're having your first eye exam, expect questions about your vision and general health history. Your answers help your eye doctor understand your risk of eye disease and vision problems. Questions might include:
During the examA clinical assistant or technician might do part of the examination, such as taking your medical history and giving the initial eye test. An eye exam usually involves these steps:
Your doctor might use several tests to check your vision and the appearance and function of all parts of your eyes. After the examAt the end of your eye exam, you and your doctor will discuss the results of all testing, including an assessment of your vision, your risk of eye disease and preventive measures you can take to protect your eyesight. Different types of eye examsEye muscle testThis test evaluates the muscles that control eye movement. Your eye doctor watches as your eyes follow a moving object, such as a pen or small light. He or she looks for muscle weakness, poor control or poor coordination. Visual acuity testThis test measures how clearly you see. Your doctor asks you to identify different letters of the alphabet printed on a chart or a screen positioned some distance away. The lines of type get smaller as you move down the chart. Each eye is tested separately. Your near vision also may be tested, using a card with letters held at reading distance. Refraction assessmentLight waves are bent as they pass through your cornea and lens. If light rays don't focus perfectly on the back of your eye, you have a refractive error. That can mean you need some form of correction, such as glasses, contact lenses or refractive surgery, to see as clearly as possible. Assessment of your refractive error helps your doctor determine a lens prescription that will give you the sharpest, most comfortable vision. The assessment can also determine that you don't need corrective lenses. Your doctor may use a computerized refractor to estimate your prescription for glasses or contact lenses. Or he or she may use a technique called retinoscopy. In this procedure, the doctor shines a light into your eye and measures the refractive error by evaluating the movement of the light reflected by your retina back through your pupil. Your eye doctor usually fine-tunes this refraction assessment by having you look through a masklike device that contains wheels of different lenses (phoropter). He or she asks you to judge which combination of lenses gives you the sharpest vision. Visual field test (perimetry)Your visual field is the full extent of what you can see to the sides without moving your eyes. The visual field test determines whether you have difficulty seeing anywhere in your overall field of vision. Types of visual field tests include:
Using your responses to one or more of these tests, your eye doctor determines the fullness of your field of vision. If you aren't able to see in certain areas, noting the pattern of your visual field loss can help your eye doctor diagnose your eye condition. Color vision testingYou could have poor color vision without realizing it. If you have difficulty distinguishing certain colors, your eye doctor might screen your vision for a color deficiency. To do this, your doctor shows you several multicolored dot-pattern tests. If you have no color deficiency, you'll be able to pick out numbers and shapes from within the dot patterns. If you do have a color deficiency, you'll find it difficult to see certain patterns within the dots. For most people, color blindness that's present at birth (congenital) is red-green, meaning you can't distinguish those colors. Most people who develop color blindness as a result of disease, such as glaucoma or optic nerve disease, can't distinguish blue-yellow. Slit-lamp examinationA slit lamp is a microscope that magnifies and illuminates the front of your eye with an intense line of light. Your doctor uses this device to examine the eyelids, lashes, cornea, iris, lens and fluid chamber between your cornea and iris. Your doctor may use a dye, most commonly fluorescein (flooh-RES-een), to color the film of tears over your eye. This helps reveal damaged cells on the front of your eye. Your tears wash the dye from the surface of your eye fairly quickly. Retinal examinationThis examination — sometimes called ophthalmoscopy or funduscopy — allows your doctor to evaluate the back of your eye, including the retina, the optic disk and the retinal blood vessels that nourish the retina. Having your pupils dilated with eyedrops before the exam keeps your pupils from getting smaller when your doctor shines light into the eye. After administering eyedrops and giving them time to work, your eye doctor may use one or more of these techniques to view the back of your eye:
Screening for glaucomaTonometry measures the fluid pressure inside your eye (intraocular pressure). This is one test that helps your eye doctor detect glaucoma, a disease that damages the optic nerve. Several methods to measure intraocular pressure are available, including:
If your eye pressure is higher than average or your optic nerve looks unusual, your doctor might use a pachymeter, which uses sound waves to measure the thickness of your cornea. The most common way of measuring corneal thickness is to put an anesthetic drop in your eye, then place a small probe in contact with the front surface of the eye. The measurement takes seconds. You might need more-specialized tests, depending on your age, medical history and risk of developing eye disease. ResultsResults from an eye exam include:
If you need corrective lenses, your doctor will give you a prescription. If your eye exam yields other abnormal results, your doctor will discuss with you the next steps for further testing or for treating an underlying condition. Clinical trialsExplore Mayo Clinic studies of tests and procedures to help prevent, detect, treat or manage conditions. How long does it take for eye dilation to wear off?Eye dilation takes time, and most eye drops will need up to 30 minutes to fully dilate the eyes. Eye dilation generally lasts between 4 and 24 hours. This margin is wide because certain factors significantly affect the duration of eye dilation.
What do they put in your eyes when they dilate them?In dilation, your doctor uses special eye drops to force the pupil to stay open. This allows them to see much more of the back of your eye, including the entire retina, the part of the retina called the macula, and the optic nerve.
Why do eye doctors put dye in your eyes?A fluorescein eye stain test can help your doctor detect corneal injuries, small foreign objects or particles in the eye, and abnormal tear production. The test may also help your doctor determine if your contact lenses are irritating your corneas or causing any damage.
Can dilation drops damage your eyes?Dilating drops cause vision to be blurred for a period of 4 to 8 hours and induce photophobia, lack of accommodation, glare, and decreased contrast threshold and high-contrast visual acuity. For elderly patients whose vision and mobility are already compromised, these visual changes can be dangerous.
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