An eye exam involves a series of tests designed to evaluate your vision and check for eye diseases. Your doctor may use a variety of instruments, aim bright lights directly at your eyes, and request that you look through a seemingly endless array of lenses. Each test during an eye exam evaluates a different aspect of your vision. A comprehensive 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 Optometrist a chance to help you correct or adapt to vision changes and provide you with tips on caring for your eyes.
What to Expect from Your Doctor
If you’re seeing a new eye doctor or if you’re having your first eye exam, expect questions about your vision history. Your answers to these questions help your eye doctor understand your risk of eye disease and vision problems. Be prepared to give specific information, including:
- Are you having any eye problems now?
- Have you had any eye problems in the past?
- Were you born prematurely?
- Do you wear glasses or contacts now? If so, are you satisfied with them?
- What health problems have you had in recent years?
- Are you taking any medications?
- Do you have any allergies to medications, food or other substances?
- Has anyone in your family had eye problems, such as cataracts, macular degeneration, or glaucoma?
- Has anyone in your family had diabetes, high blood pressure, heart disease or any other health problems that can affect the whole body?
If you wear contact lenses or glasses, bring them both to your appointment. Your eye doctor will want to make sure your prescription is the best one for you.
What to Expect from the Examination
- First, you will be asked about your medical history and any vision problems you might be experiencing.
- Next, your doctor measures your visual acuity, assesses your need for glasses and examines your eyes for signs of disease.
- Finally, your eye doctor checks your eyes using a light to ensure the interior and exterior parts of your eyes are healthy.
Part of the examination, such as taking your medical history and the initial eye testing, may be performed by a technician who assists your doctor. Several different tests may be performed during the eye exam. These tests are designed to check your vision and to examine the appearance and function of all parts of your eyes.
At the end of your eye exam, your doctor will provide you with a detailed assessment of your vision, along with any risks you should be aware of and preventive measures you can take to protect your eyesight.
Normal results from an eye exam include:
- 20/20 vision
- Good tracking or eye movement skills
- Good peripheral vision
- Normal-appearing structures of the eye upon examination
- No evidence of cataract, glaucoma, or retinal (macular) degeneration
Your doctor may give you a prescription for corrective lenses. If your eye exam yields abnormal results, your doctor will discuss with you any necessary steps for further testing or for treating an underlying condition.
A series of tests will be performed to determine how the nervous system (brain) works with the eyes. Tracking of the eyes into six different directions, peripheral vision, and pupil function are all part of a simple set of tests done during an eye exam. These tests help your Optometrist determine how well your eyes communicate with the brain. It can help check for a number of serious conditions such as brain tumor, aneurysm, concussion, and stroke.
Visual Acuity Test
This test measures how clearly you can see from a distance and while reading. Your doctor will ask you to identify different letters of the alphabet printed on a chart (Snellen 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. Your doctor may start with 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 having you look through a Phoroptor, a mask-like device that contains wheels of different lenses, to 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.
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 eventually wash the dye away.
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. The retinal examination takes only a few minutes, but if you’re given eyedrops to dilate the pupils, their effects may not wear off for several hours. Your vision will likely be blurry, and you may have trouble focusing your eyes. If you’re particularly sensitive to light, you may need to wear dark glasses (or sunglasses) for a short time. 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 effects of the eyedrops wear off.
The most common type of tonometry is the dreaded “air puff” test. This is a test that measures the pressure inside your eyes and is a screening test for glaucoma. It does not require the use of any eye drops in the eye, however, it can be startling to you — especially for first-timers. If you prefer, there are other methods for acquiring this measurement. Applanation tonometry is a less-startling method of measuring eye pressure, but does require a short-acting numbing drop in each eye. You can always request applanation tonometry, if you do not like the “air puff”.
Besides these basic evaluations, you may need more specialized tests, depending on your age, medical history, family history, or if any of the tests above are abnormal.