Because most eye disorders are symptomless in their early stages, many people are unaware that they have one. Surveys by researchers at Johns Hopkins have found that about one third of people with eye disease were unaware of it and that more than one third of those ages 65 to 84 had not visited an ophthalmologist (eye doctor) in the past year. Periodic visits to an eye care specialist are needed to detect conditions early enough to allow effective treatment. Regular checkups are particularly important for people over age 65, those with risk factors for serious eye disease, those in fair or poor general health, and those with diabetes.
Before cataract surgery, the ophthalmologist will obtain a medical history, which includes past and current medical conditions, current medications, and allergies. A-scan ultrasonography, a test that uses sound waves or a laser to measure the length of the eyeball, is routinely performed. The eyeball length is used to determine the appropriate focusing power of the intraocular lens implant, a plastic lens that replaces the lens removed during cataract surgery. If the surgeon cannot see the retina in the back of the eye because the cataract is too opaque, another test called B-scan ultrasonography is used. This test uses reflected sound waves to look at structures in the back of the eye.