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An eye exam is one of the best ways to protect your vision because it can 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 eye care specialists can give you expert tips on reducing eyestrain and caring for your eyes.
What type of doctor do you need?
Ophthalmologists are medical doctors who provide full eye care, such as giving you a complete eye exam, prescribing corrective lenses, diagnosing and treating complex eye diseases, and performing surgery.
Optometrists provide many of the same services as ophthalmologists, such as evaluating your vision, prescribing corrective lenses, diagnosing common eye disorders and treating selected eye diseases with drugs. But you’ll likely be referred to an ophthalmologist for more complex eye problems and for conditions requiring surgery.
What happens during an eye exam?
A complete eye exam involves a series of tests designed to evaluate your vision and check for eye diseases. It doesn’t hurt. Your doctor may use odd-looking instruments, aim bright lights directly at your eyes and request that you look through a seemingly endless array of lenses. Each test evaluates a different aspect of your vision.
The eye exam usually begins with your doctor asking about your medical history and any vision problems you might be experiencing. Next, your eye doctor makes a quick check of your eyes using a light to ensure the exterior parts of your eyes are functioning correctly. Finally, your doctor measures your visual acuity, assesses your need for glasses and examines your eyes for signs of disease. Part of the examination, such as taking your medical history and the initial eye test, may be performed by a technician who assists your doctor.
Tests that are performed
Eye muscle test
This test examines the muscles that control eye movement, looking for weakness or poor control. Your eye doctor looks at your eyes as you move them in six specific directions and as you visually track a moving object, such as a pen.
Visual acuity test
This test measures how clearly you can see from a distance. Your doctor will ask you to identify different letters of the alphabet printed on a chart positioned usually 20 feet away. The lines of type get smaller as you move down the chart. You cover one eye and read aloud, then cover the other eye and read aloud.
Refraction refers to how light waves are bent as they pass through your cornea and lens. A refraction assessment helps your doctor determine a corrective lens prescription that will give you the sharpest vision. If you don’t need corrective lenses, you won’t have a refraction assessment.
Your doctor may use a computerized refractor to measure your eyes and estimate the prescription you need to correct a refractive error. 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.
Your eye doctor fine-tunes this refraction assessment by asking you to look through a Phoropter, a mask-like device that contains wheels of different lenses, and judge which combination gives you the sharpest vision. By repeating this step several times, your doctor finds the lenses that give you the greatest possible acuity.
Visual field test (perimetry)
Your visual field is the area in front of you that you can see without moving your eyes. The visual field test determines whether you have difficulty seeing in any areas of your peripheral vision — the areas on the side of your visual field. There are a few different types of visual field tests:
A slit lamp is a microscope that enlarges and illuminates the front of your eye with an intense line of light. Your doctor uses this light to examine the cornea, iris, lens and anterior chamber of your eye.
When examining your cornea, your doctor may use eye drops containing fluorescein (flooh-RES-ene) dye. The orange dye spreads across your eyes to help your eye doctor detect tiny cuts, scrapes, tears, foreign objects or infections on your cornea. Your eyes’ tears will wash the dye away.
Retinal examination (ophthalmoscopy)
A retinal examination — sometimes called ophthalmoscopy or fundoscopy — examines the back of your eye, including your retina, optic disk and the underlying layer of blood vessels that nourish the retina (choroid). Usually before your doctor can see these structures, your pupils must be dilated with special eye drops. The eye drops may sting briefly and might cause a medicinal taste in your mouth as the medication drains from your tear ducts into your throat.
After administering eye drops, your eye doctor may use one or more of these techniques to view the back of your eye:
The retinal examination takes five to 10 minutes, but if you’re given eye drops, their effects won’t wear off for several hours. Your vision will be blurry, and you’ll have trouble focusing your eyes. You may not be able to drive, so make sure you have another way back to work or home. Depending on your job, you might not be able to work until the eye drops wear off.
Glaucoma test (tonometry)
Tonometry measures your intraocular pressure — the pressure inside your eyes. It helps your eye doctor detect glaucoma, a disease that causes pressure to build up inside your eyes and can cause blindness. Glaucoma can be treated if it’s caught early.
Methods your eye doctor may use to test your eyes for glaucoma include:
This test measures the amount of force needed to temporarily flatten a part of your cornea. Fluorescein, the same orange dye used in a regular slit-lamp exam, is usually put in your eye to make your cornea easier to see. You’ll also receive eye drops containing an anesthetic. Using the slit lamp, your doctor moves the tonometer to touch your cornea. It won’t hurt, and the anesthetic will wear off within two hours.
Hope this helps with any worries that you may have about what happens during an eye exam. If you have questions or comments, please post them and I will be more than happy to answer them to the best of my ability.