Are There Different Types of Cataracts?
There are three primary types of age-related cataracts: Nuclear Sclerotic, Cortical, and Posterior Subcapsular. As a person ages, any one type, or a combination of any of these three types, can develop over time:
This is the most common type of age-related cataract, caused primarily by the hardening and yellowing of the lens over time. "Nuclear" refers to the gradual clouding of the central portion of the lens, called the nucleus; "sclerotic" refers to the hardening, or sclerosis, of the lens nucleus.
As this type of cataract progresses, it changes the eye's ability to focus, and close-up vision (for reading or other types of close work) may temporarily improve. This symptom is referred to as "second sight," but the vision improvement it produces is not permanent.
A nuclear sclerotic cataract progresses slowly and may require many years of gradual development before it begins to affect vision.
"Cortical" refers to white opacities, or cloudy areas, that develop in the lens cortex, which is the peripheral (outside) edge of the lens. Changes in the water content of the lens fibers create clefts, or fissures, that look like the spokes of a wheel pointing from the outside edge of the lens in toward the center.
These fissures can cause the light that enters the eye to scatter, creating problems with blurred vision, glare, contrast, and depth perception. (See What Kinds of Vision Changes Are Related to Cataracts? for more information.) People with diabetes are at risk for developing cortical cataracts.
Photo of an eye with a cortical cataract.
Source: National Eye Institute
This type of cataract begins as a small opaque or cloudy area on the "posterior," or back surface of the lens. It is called "subcapsular" because it forms beneath the lens capsule, which is a small "sac," or membrane, that encloses the lens and holds it in place.
Subcapsular cataracts can interfere with reading and create "halo" effects and glare around lights. People who use steroids, or have diabetes, extreme nearsightedness, and/or retinitis pigmentosa may develop this type of cataract. Subcapsular cataracts can develop rapidly and symptoms can become noticeable within months.
Please note: A cataract is not a tumor, nor is it a "film" or tissue growth that develops over the cornea, or front surface of the eye. Although the majority of cataracts are not visible to the naked eye, there are some instances in which the pupil can appear white because the lens is completely clouded by a very dense cataract.
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