At some point in life, almost everyone experiences some difficulty with their vision. Most people have to turn to corrective lenses at some point, but that is only one small part of potential eye conditions. Glaucoma, cataracts, retinal detachment, and disorders of the cornea are just some of the more serious eye disorders that can develop. Some of them, like glaucoma, show no symptoms until they begin compromising your vision.
Such problems are much easier to deal with if you have the preventative knowledge from a regular eye exam. Regular eye exams should be scheduled every other year for people with healthy vision. If you have corrective lenses or are over the age of 40, more frequent checkups are advised. Some cases, like those with diabetes demand annual visits to the doctor for a vision exam.
Optometrists and ophthalmologists have a variety of tests to check your vision. Vision tests usually begin with an eye chart and progress to more intricate tests to check the minute structure of your eye. The course of a vision exam is dictated by your individual needs and may include any number of tests.
Comprehensive eye exams usually take about an hour and consist of the following tests:
This is the classic eye chart test. You’ll start with reading a chart far away and sometimes read a handheld sign at arms length to test your vision. This tests the range of your vision and your visual acuity, or the ability to focus on far field objects. Visual acuity declines with age, as the muscles in your eyes lose tone.
By some estimates, almost five percent of people suffer from color blindness. Testing for color blindness tests your color recognition and is also useful screening for more serious illnesses. Multiple sclerosis and some liver diseases can lead to color blindness.
A cover test determines the ability of your eyes to work together when focusing on objects. While you focus on a distant point, the doctor covers each eye individually, judging the adjustment speed of the uncovered eye.
If the uncovered eye moves to locate the focal point, it could be a sign of strabismus or a slight binocular vision problem, which may cause eye strain or “lazy eye.” Isolating the eyes helps to uncover a problem that may be masked by the eyes working in unison.
For this test, lights you focused on the large “E” of the eye chart in a dark room. As you focus on the “E”, the doctor exposes your eyes to a beam of light filtered through different lenses. Given the reflection of the light from your eyes, the doctor can approximate a diopter for your prescription. This is a crude assessment and is only the first step in determining the correct subscription for you.
While the retinoscopy exam gives a general prescription, the refraction exam fine-tunes it. While you look through different lenses in sequence with a phoropter placed before your eyes, you decide which one of the two gives you a clearer picture. Gradually, the doctor narrows the lenses down to the correct lens prescription for you.
Your prescription may also be adjusted using automatic machines like an aberrometer or autorefractor.
A slit lamp, also known as biomicroscope, is an instrument that creates an enlarged view of the eye. The instrument is used for examining the structure on the face of the eye, like conjunctiva, iris, and cornea, or inner structures like the macula, optic nerve, or retina.
There are some conditions that are only diagnosed by looking into the structure of the eye, and a skit-lamp exam, with or without dilation is necessary. This isn’t always the most comfortable experience, since it involves a doctor looking into your eye with a bright light at close range, but the test is short.
Glaucoma, caused by high pressure on eyes, can result to loss of eyesight. Since the disease generally doesn’t offer any symptoms, it is vital to have this test done. Early diagnosis of glaucoma can prevent loss of vision.
Patients with diabetes are at high risk for developing glaucoma and can expect to have frequent testing for the disorder.
This test is performed in a variety of ways, but each measures the pressure inside the eye.
Pupil dilation is an effective way to get a deeper look at the internal structure of the eye and may be incorporated into the slit lamp exam. A solution, applied topically to the eye, dilates the pupils, which takes about 20 to 30 minutes for eyes. Once the eyes are fully dilated and the exam is over, it takes about 30 to 60 minutes for eyes to return to normal function.
Since the pupils are enlarged as a result of this test, you may find it difficult to focus on closer objects. The effect is temporary and use of sunglasses is recommended after having undergone this test.
Being Prepared for Your Exam
Your doctor evaluates the results of these tests in context with a variety of information, including the following:
- Family History – Your family history represents significant information on risk factors you have for developing eye disorders. How many people in your family use corrective lenses? What are their prescriptions for? In addition, take stock of any family history for different types of cancer, heart disease, and diabetes. There are a number of eye disorders that present alongside seemingly unrelated medical problems.
- Allergies – It’s often difficult to appreciate the ways that allergies can impact us. Don’t leave anything out. You might not realize the presence of an allergen in your life, but a doctor could help you put the pieces together.
- Medications – Your doctor will ask you about any medications or recreational drugs you use. Leave nothing out of this history! Even a medication that you have tolerated for years may suddenly contribute to adverse health effects.
- Recent Events – Has anything in your life changed recently? Stress is triggered by a variety of sources and they aren’t always obvious. Stress causes the cardiovascular system to work harder, which might damage parts of the eye. If there have been any changes to your routine or your environment, new surroundings or activities might be affecting your health.