Eye cataracts can be diagnosed by an optometrist or an ophthalmologist by performing a series of tests, usually included in a comprehensive eye examination. The following tests help doctors diagnose eye cataracts and determine their severity.
- Visual Acuity: A visual acuity test measures your quality of vision at certain distances. Your doctor will ask you to read letters of various sizes from a chart. Your eyes will be tested individually and together to measure the accuracy of your eyesight at different distances. A visual acuity test is an easy, painless, and quick way to diagnosis cataracts, although more tests will be needed to make sure cataracts are the cause of your vision problems.
- Contrast Sensitivity: Contrast sensitivity testing is similar to visual acuity testing but places greater emphasis on how cataracts can decrease image contrast due to light scattering and glare caused by the cataract. Eye doctors consider contrast sensitivity testing to be a more realistic measurement of true quality of vision.
- Slit Lamp: A slit lamp is a special type of microscope that magnifies your eye so your doctor can examine the lens to determine the presence and severity of a cataract. Your doctor will ask you to place your chin on the chin rest of the slit lamp. A light will then be directed at your eye. By looking through the slit lamp, your doctor can examine the lens to determine the degree to which it is clouded.
- Pupil Dilation: Pupil dilation is a common test used in diagnosing cataracts. Clouding of the lens is not noticeable until a cataract reaches an advanced stage. When your eye is dilated, however, the pupil increases in size, offering a view of your entire lens. By thoroughly examining the lens, a doctor can determine whether or not a cataract is affecting your quality of vision.
American Optometric Association. "Clinical Practice Guideline: Care of the Adult Patient With Cataract." American Optometric Association, 1995.