Wondering what to expect during your exam? To check for vision problems and eye disorders, the doctor may use bright lights, instruments, an array of lenses, special eye drops, and other techniques:

Visual Acuity Test: To measure how clearly you see at a distance, you identify letters of various sizes on a printed chart, typically positioned 20 feet away.  Or you may view a chart inside a machine.  The type gets smaller as you move down its rows.  You’ll cover one eye, then the other, as you read the letters aloud.  Your score will then be compared to how someone with normal vision sees at that distance.

Refraction Assessment: If your eyesight isn’t perfect, this test helps your doctor determine the right prescription for glasses or contact lenses.  You look into a mask-like device called a Phoroptor, which holds lenses of various strengths.  As you focus on an eye chart, your doctor will flip two lenses into your view and ask it the letters are more or less clear.  By repeating this step with different combinations, the doctor can pinpoint the power that gives you the best possible vision.  If you currently wear glasses or contacts, the doctor will check to see whether your prescription has changed.

Pupil Size and Reactivity Test: The doctor shines a light into each eye to see whether both pupils are the same size and contract normally.  Pupil problems can be a warning sign of such disorders as high blood pressure, multiple sclerosis, or glaucoma.

Eye Movement Exam: You track a moving target, such as the doctor’s hand or a pen.  As your eyes travel up and down, and from side to side, the doctor checks whether they are properly aligned.  This test screens for strabismus - a disorder in which the eyes don’t move together when focusing on an object-and other eye movement disorders.

Visual Field Exam: There are several ways to test your peripheral (side) vision, but they all involve covering one eye and staring straight ahead with the other.  In the most basic test, your doctor moves his hand through your field of vision, and asks if you can see how many fingers he’s holding up.  Or you may watch a screen as dots if light flash.  Usually, you’ll press a button each time you see a dot, enabling a computer to map your field of vision.  The test detects blind spots due to glaucoma, a stroke, or other ailments.

Slit Lamp Exam: A slit lamp is a microscope with a thin beam of light, used to examine the front of each eye, including your iris (colored portion), sclera (white area), eyelid, lens, and cornea, under magnification. The doctor may use special eye drops to dilate (expand) your pupils, then repeat the exam, to view the retina and back of the eye.  The test checks for cataracts, macular degeneration, diabetes complications, cornea scratches or infections, and chronic dry eye.  The eye drops take about 15 minutes to work and may sting briefly.  You might notice a medicinal taste in your mouth as the drops drain from your tear ducts into your throat.  After the exam, your eyes will be more sensitive to light for a few hours, until the dilating drops wear off.

Schirmer Tear Test: To gauge the moistness of your eyes, the doctor can place extremely thin strips of blotting paper under your lower eyelids.  It doesn’t hurt.  After five minutes, the doctor checks how much of the strip is saturated with tears.  

Glaucoma Test: Also known as tonometry, this test gauges the pressure inside your eyes, which goes up if you have glaucoma.  First, the doctor uses special eye drops to numb your eyes.  He may also add a squirt of orange dye to make it easier to view your cornea.  Using a little probe on the slit lamp, he gently presses on each cornea to measure eye pressure.  It doesn’t hurt, and the numbing drops wear off in about 20 minutes.

Getting The Results

After your exam is over, the doctor will go over the findings with you, alert you to any risks, and suggest steps to protect your vision, which could be as simple as having another checkup in one or more years.  If your current glasses or contacts aren’t doing the trick anymore, you’ll get a prescription for new ones.  If other eye problems are detected, your doctor will explain treatment options, which may include eye drops, medication, or other therapies.

What if your previously perfect vision isn’t what it used to be?  If the problem is mild-you can still pass the driver’s eye test, read comfortably, and safely perform everyday tasks-you may decide not to get corrective lenses yet.  But if it’s impairing you even moderately, then it’s time for glasses or contacts.  Don’t like those solutions?  Ask if you’re a candidate for laser surgery to reshape your cornea, which can enhance your vision.

What You Should Know About Eye Exams