Tests to Diagnose A Cataract

Cataracts are fairly easy to diagnose. Nevertheless, for the most accurate diagnosis, there are a number of advanced tests that your doctor may use. Utilizing these diagnostic tools, your doctor can also check for an additional eye disease, such as glaucoma or macular degeneration.

Visual Acuity Test

Pineapple When you think of a routine eye exam, this test is probably what you picture. Your doctor will ask you to read a series of letters off of a Snellen eye chart posted 20 feet away from you. This test allows him or her to detect any significant changes in your vision.
If you have already been diagnosed with cataracts, and your vision has degenerated to 20/40 or below, your doctor may recommend surgery. In some cases, you may have a good score on this test, but you still present with other cataract symptoms, such as light sensitivity or blurred vision. When this occurs, your ophthalmologist will likely recommend more tests to determine whether cataracts are, in fact, responsible for your symptoms.

Slit Lamp Exam

Pineapple Your doctor will give you eye drops to dilate your pupil. By shining a light on the front of your eye, he or she can usually detect any white spots on your lens, even if they are very minute. The slit lamp exam often allows for extremely early diagnosis, so that your ophthalmologist can detect cataracts before they begin to affect your vision. During the test, your doctor will likely use a magnifying lens to examine your retina and optic nerve. Although this step is not necessary for cataracts detection, it enables your doctor to check for other serious eye conditions.

Glare and Contrast Sensitivity Tests

Pineapple During a glare test, you will be asked to read the Snellen chart under various lighting conditions. If you have difficulty discerning the letters under very bright light, this could be a good indication of cataracts.
Contrast sensitivity tests use different kinds of charts; instead of the letters getting smaller as they go down the chart, they "fade," or contrast less with the white background. If you are unable to read all but the most defined rows of letters, this, too, could be an indication of cataracts.

Ishihara Color Test

Pineapple Named after its designer, Dr. Shinobu Ishihara, this test uses a series of plates covered with colored dots. The dots vary in color, forming a number in the center of the plate. Those with an inability to distinguish hues on the blue-green end of the spectrum will not be able to see the numbers. If you have not been previously diagnosed as color blind, and you do not pass the Ishihara color test, you may be suffering from advanced cataracts.

Tonometry Test

Pineapple Your ophthalmologist will direct a puff of air towards your eye, and it will measure the intraocular pressure (IOP), determined by the amount of vitreous fluid inside your eye. Although tonometry tests are most commonly used to diagnose glaucoma, it is important that your doctor be as thorough as possible during cataract diagnosis. When left undiagnosed and untreated, glaucoma, macular degeneration, and similar eye diseases can have dramatic consequences for your vision and ocular health.

Different Types of Cataracts

Posterior polar cataract of an 8 year old boy in left eye
Nuclear sclerosis cataract of a 70 year old male
Cortical cataract of a 60 year old male
Retroillumination of cortical cataract
Posterior subcapsular cataract of a 16 year old girl with IDDM
Intumescent cataract of a 55 year old male
Anterior subcapsular cataract having back shadow
Posterior subcapsular cataract by retroillumination
Nuclear sclerosis and posterior polar cataract of a 60 year old female