According to the National Eye Institute, part of the National Institutes of Health, cataract types are subdivided accordingly:
• Age-related cataracts
The majority of cataracts are related to aging.
• Congenital cataracts
Some babies are born with cataracts or develop them in childhood, often in both eyes. Some congenital cataracts do not affect vision, but others do and need to be removed.
• Secondary cataracts
Secondary cataracts develop primarily as a result of another disease occurrence in the body (i.e., diabetes). Secondary cataract development has also been linked to steroid use.
• Traumatic cataracts
Eye(s) that have sustained an injury may develop a traumatic cataract either immediately following the incident, or several years later.
Other sources, including the American Academy of Ophthalmology, describe the different types of cataracts according to the cataract location on the eye lens, including:
• Nuclear cataract
This is the most common type of cataract, and the most common type associated with aging. Nuclear cataracts develop in the center of the lens and can induce myopia, or nearsightedness - a temporary improvement in reading vision which is sometimes referred to as "second sight." Unfortunately, "second sight" disappears as the cataract grows.
• Cortical cataract
This type of cataract initially develops as wedge-shaped spokes in the cortex of the lens, with the spokes extending from the outside of the lens to the center. When these spokes reach the center of the lens they interfere with the transmission of light and cause glare and loss of contrast. This type of cataract is frequently developed in persons with diabetes, and while it usually develops slowly, it may impair both distance and near vision so significantly that surgery is often suggested at an early stage.
• Subcapsular cataract
A subcapsular cataract usually starts as a small opacity under the capsule, at the back of the lens. This type of cataract develops slowly and significant symptoms may not occur until the cataract is well developed. A subcapsular cataract is often found in persons with diabetes, myopia, retinitis pigmentosa, and in those taking steroids.