A comprehensive eye exam consists of a variety of tests and procedures. This complete evaluation of the eyes may be performed by an optometrist or an ophthalmologist. The tests can take an hour or more, depending on your eye health, age and vision requirements. The usual eye and vision tests that you will undergo during a comprehensive eye exam include:
Test of Vision:
Usually, the first tests during the comprehensive eye exam are tests for vision. These include tests for visual acuity and color vision.
Test for Visual acuity
This test measures the sharpness of your vision. To test you distance vision, the doctor will project an eye chart on a screen. She will then ask you to read them out loud.
To measure your near vision, your doctor will ask you to read from a small, hand-held acuity chart.
This is to determine if you have a refractive error, or need glasses for better vision.
Test for color vision
The doctor will ask you to read from a small color vision book, called Ishihara’s charts. This test checks your color vision, and screens for color blindness.
Test for eye alignment
Cover and Cover-Uncover Tests
The cover test determines the alignment of your eyes. Your doctor will ask you to focus on a target in the distance. She will then cover one eye, and observe the eye alignment. After that, she will uncover the eye, and repeat the test for the other eye. Then, the doctor will also cover each eye alternately and observe your eye movements. After this,
she will repeat the test with you looking at a near object.
This test is performed to diagnose squint or strabismus, and also lazy eye.
Ocular Motility Testing
The doctor will then check your eye movements or eye motility. With your head held still, you will have to follow the slow movement of a hand-held light. Your doctor may also use a target, like a pen, to check for double vision or diplopia in various gazes.
Refraction
Your eye doctor will ask you to sit comfortably with your chin rest in a machine called the autorefractometer. You will then be asked to look at an image or point inside the machine. This machine checks the approximate power of your glasses. Alternatively, your doctor may perform a retinoscopy.
During retinoscopy, the room lights will be dimmed and you will be asked to look ahead. The doctor will then shine a light in your eyes, and place various lenses in front of your eyes. This estimates the lens powers for the best distance vision. Thereafter, the doctor will then put a trial frame with lenses, or a phoropter, to fine tune your power of glasses. In case you need contact lenses, the doctor may perform some extra tests.
Slit Lamp Exam
The slit lamp is actually a binocular microscope. Your eye doctor uses it to see a magnified image of your eye. During the examination, you will be asked to place your chin in the chin rest, and to make sure that your forehead rests against the machine. Thereafter, the doctor will examine the front of your eye. This test will check your eyelids,
cornea, conjunctiva, iris, and lens.
After this, the doctor will use a small hand-held lens, to look at the back of your eye. This test is for the vitreous, retina and the optic nerve.
A wide range of eye conditions and diseases can be detected with the slit lamp exam, including cataracts, macular degeneration, corneal ulcers and diabetic retinopathy, etc.
Test for eye pressure or “Glaucoma Test”
Non-contact tonometry
The most commonly done test for eye pressure is the air puff, or non-contact tonometry, NCT. The doctor will ensure that your chin is secured in the chin rest, and your forehead resting comfortably against the machine. Once you look
at the light inside the apparatus, the doctor will press a button. You will feel a puff of air in your eye. This is completely painless, and the instrument does not touch your eye. You might, however, be startled by the accompanying noise.
Applanation tonometry
The alternate way of measuring eye pressure or intraocular pressure is applanation tonometry. For this test, your doctor will first put eye drops in your eyes. These drops will make your eyes numb. Then the doctor will either put yellow colored drops, or touch a paper impregnated with the yellow eye to your eyes. After this, the doctor will ask you to sit at the slit lamp, and look straight ahead. She will then measure your eye pressures using a blue light. You will see a prism like instrument approaching the eye. Even though the prism with gently touch your eye, the procedure is completely painless.
Pupil Dilation
The doctor will not always order pupil dilation. However, a dilated evaluation is an integral part of the comprehensive eye exam. In case your doctor needs a detailed view of your retina, she will ask for drops to be put in your eyes. These drops enlarge your pupils, thus allowing a better view of the structures at the back of the eye. These drops will be put two or three times, and need about half an hour to become effective.
Dilation makes your eyes sensitive to light and glare. In fact, your reading will also be affected. Consequently, your doctor will insist you do not drive after this test. The effect of these drops typically wears off in about two to three hours.
Dilated retina evaluation
Generally, your doctor will test your retina on the slit lamp as explained above. After dilation, the doctor may ask you to lie down or recline in your chair. She will then use a head mounted source of lght to performa test called indirect ophthalmoscopy. This light is a little uncomfortable.
Your doctor will ask you to focus on your outstretched thumb. She will move your thumb in various positions, in order to examine the retina in greater detail.
Things to remember
Answer all questions truthfully
Your doctor will take a detailed history about your eyes and general health. Make sure you answer all these questions truthfully. In fact, you should carry all your previous records as well.
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Who will do the tests
Your doctor will do some of these tests herself. Other tests will be done by an optometrist. In certain countries, the optometrists perform all of these tests, and only refer patients to the eye doctor if necessary.
What about additional tests
In case your doctor thinks they are necessary, she will order additional tests. These are done to confirm or rule out possible diseases. Tests that may be prescribed are retinal or fundus photography, gonioscopy, corneal pachymetry, corneal topography, optic nerve or macular scans (OCT, GDx, HRT), ultrasound, visual field testing and biometry.
How much time will it take
Hopefully, you will not have to wait to see your doctor. In that case, a routine eye check, without dilation should take about ten to fifteen minutes. In case your doctor dilates your eyes, you will need an additional or so.
Driving back after the comprehensive eye exam
When you schedule your appointment, make sure you ask if you will need a pupil dilation during your scheduled comprehensive eye exam. Remember, you will not be able to drive back on your own, as your vision will be fuzzy. In fact, try and carry a pair of sunglasses to avoid the glare.
Things to ask your doctor before you walk out after your comprehensive eye exam
• Is my vision 100% with glasses/ contact lenses?
• Is my eye pressure fine?
• Are my retina, cornea and optic nerve in good health?
• Any dietary restrictions or recommendations?
• In case of tests, what are the permitted timelines for scheduling them?
• In case of disease, when can I expect to feel better?
• How do I reach you in an emergency?
• When do I come back?
