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What You Need To Know About Eye Examinations
By: James Auran, MD
When Should I Have My Eyes Examined?Adults
If you are an adult without risk factors for eye disease, The American Academy of Ophthalmology recommends that you have an eye examination at least once between the ages 20 and 39, every two to four years between ages 40 and 64, and every one to two years if you are 65 or older. If you are African-American or have a family history of glaucoma, you should be examined every three to five years between 20 and 39 years of age, every two to four years between ages 40 and 64, every one to two years if you are older than 65. People with diabetes should receive an examination by an eye doctor at least once a year.
The American Academy of Ophthalmology and the American Association for Pediatric Ophthalmology and Strabismus (http://med-aapos.bu.edu/AAPOS/Screening.html) recommend that a pediatrician or family physician examine infants in the nursery and that high-risk infants be examined by an ophthalmologist. Children’s eyes should be screened by their pediatrician, family physician, or ophthalmologist at ages six months, three and one-half years, and five years. After that, screening should be performed at routine school examinations or if eye symptoms are present. Routine examinations by an ophthalmologist are not of significant benefit.
Who Should Examine My Eyes?Eye examinations are performed by eye doctors--ophthalmologists (eye MDs) or optometrists (doctorates of optometry). In some cases, assistants or technicians may perform portions of the examination. In general, the quality of the examination depends on the training, experience, and intelligence of the examiner, as well as the thoroughness and duration of examination.
Remember to bring a list of all your medications. If your history is complicated, old medical records or a report from your previous doctor can be invaluable. If you anticipate that the doctor will dilate your pupils (ask about this at the time you schedule the appointment), plan on not driving for four hours after the examination. Clarify with the doctor’s office your insurance coverage and the procedure that you and the doctor must follow to obtain optimum insurance coverage for the visit. In particular, if your insurer requires pre-certification, make sure the doctor’s office has this before you are seen.
The Eye Examination
The following is a description of the various stages of an eye exam:
The history you provide your eye doctor is often the most important part of the encounter. Be prepared to provide a comprehensive medical history. A thorough history includes family history (especially of glaucoma, cataracts, retinal detachments, macular degeneration, diabetes, migraines), and your medications, allergies, and previous eye problems. When giving a history of medications to your doctor, remember to include aspirin, asthma inhalers, steroid nasal sprays, steroid skin ointments, vitamins, and nutritional supplements, all of which can affect the eye or impact upon eye surgery. If you have ever been told that you have lazy eye (amblyopia), let your doctor know. It is also important to let the doctor know if you are or could be pregnant, or if you are nursing a child. Medical history information is often obtained by the doctor via a written questionnaire.
Many people are squeamish about their eyes, which is perfectly natural. An experienced eye doctor can make the examination experience minimally uncomfortable. The purpose of the exam is to determine how well the eye is working and if all its parts are intact.
The examination usually begins with testing your eyesight by reading the eye chart, at far, intermediate (computer screen distance), and near (reading) distances. If your vision is not as good as it should be, refraction may be performed, in which lenses are placed in front of the eye to optimize your visual acuity. The eye doctor may then work with you to determine if glasses or contact lenses are appropriate and, if so, what type(s) will work best for you.
The pupil is the opening in the center of your iris (colored portion of the eye) through which light passes into the back of the eye. When you look at another person's eye, the pupil is the black spot in the center of the iris. The doctor will test your pupil function, by shining a flashlight into each eye separately and then alternating between the eyes. The doctor may crudely test your peripheral vision by having you count his/her fingers (or by having you correctly indicate when they are moving) when they are positioned well away from the direction at which you are looking.
The muscles controlling the eyes will be tested to determine if the eyes move appropriately in every direction: alone and together as a pair. Any double vision or tendency towards double vision will be evaluated and treated if appropriate.
Slit lamp examination
The next portion of the examination will occur with you sitting at the slit lamp, a binocular microscope that the doctor uses to examine your eyes under high magnification. It is very important that the doctor positions you comfortably or it will be difficult to hold still during the examination. The slit lamp allows the doctor to perform a detailed examination of the lids, the white of the eye (conjunctiva and sclera), the cornea (the clear front window in front of the iris and pupil through which light enters the eye), the iris, and your crystalline lens.
The front part of your eye is filled with fluid, which continually percolates through the eye, bringing oxygen and nutrients to the cornea and lens, neither of which has a supply of blood. During the slit lamp examination, a measurement of the fluid pressure within the eye will be performed to determine if you might have glaucoma. Glaucoma is a disorder in which the fluid pressure in the eye goes up, pressing on the optic nerve and eventually damaging or destroying it. Anesthetic eye drops will be applied to your eyes prior to this test. These drops sting for up to a minute and then leave the eye numb and feeling full or heavy for 10 to 15 minutes. Your throat may also feel numb from the drops draining into your nose and throat via your tear drainage system.
The measurement of eye pressure involves touching each eye with a probe, called an applanation tonometer, for just a few seconds. The surface of this probe is smooth plastic and it is possible, but highly unlikely, to scratch the surface of your eye during this test. The back of the eye may be examined with a very intense light during the slit lamp examination.
The pupil is typically small enough to limit the doctor’s view into your eye. For this reason, dilating eye drops, which enlarge the pupil for two to four hours, are routinely given prior to examination of the back of the eye. These drops should not hurt because the eye should still be numb from the anesthetic drops. With dilation, you may find your vision blurred and the world will appear very bright, especially outdoors. The instruments used to examine the back of the eye project intense light into your eyes. Reducing the intensity of the light may limit the doctor’s view, but if the bright light is too uncomfortable, it is appropriate for you to ask that the intensity be reduced if possible. Fortunately, the eye adapts somewhat to the intense light and the discomfort often abates as the examination progresses.
The back of your eyes will be examined with the hand-held direct ophthalmoscope. This provides a high magnification view of the very back of your eye and allows the examiner to evaluate the retina (the nerve layer in the back of the eye that contains the sensory cells, or photoreceptors), blood vessels, and optic nerve. This portion of the exam is particularly helpful in identifying age-related macular degeneration and abnormalities of the optic nerve such as glaucoma damage.
After donning a headset, the doctor next examines your eye with a binocular indirect ophthalmoscope. This gives the doctor a panoramic view of the entirety of the back of your eye, looking for retinal holes, tears or detachments, moles, tumors, or abnormal blood vessels. Because the doctor can only view a portion of the back of the eye at any one time, he or she will instruct you to look in different directions in order to view all of the posterior pole.
Pupillary dilation can distort the vision enough to impair the ability to drive for two to four hours. You can ask your doctor to use weak dilating drops (e.g., 0.5 percent tropicamide) and give you reversing drops (dapiprazole or Rev-Eyes) to hasten recovery after dilation.
Specialized examinations: visual fields
Should there be a suspicion that your peripheral vision is impaired, or could be in the future, your doctor may order a formal visual field test. Computerized visual field testing (e.g., Humphrey visual fields) is most commonly used. In this test, you will be asked to look at a central, fixed point while tiny lights are illuminated in the periphery and you will be asked to press a button when you see the peripheral light go on. The test takes about 20 minutes.
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