Types of Cataracts

Although all cataracts involve a changing of the eye's lens, several types of cataracts exist. Cataracts may develop as a result of aging or may appear early in life. Different portions of the lens may be affected more than others. Eye doctors classify cataracts according to their location and origin.

Types of Cataracts by Location

Cataracts are classified by doctors according to the location of the opacity, or clouding, of the lens.

Nuclear Sclerotic Cataract

A nuclear sclerotic cataract is the most common type of age-related cataract. This type of cataract causes gradual yellow cloudiness and hardening of the central part of the lens called the nucleus. Changes in vision are usually gradual.

In some cases, patients may see an actual improvement in near vision before their vision deteriorates to a significant degree. Referred to as "second sight," this stage is usually only temporary.

Cortical Cataract

A cortical cataract generally appears as a cloudy opacity in the part of the lens called the cortex. The cortex consists of the peripheral, or outer part, of the lens. These cataracts often resemble wheel spokes that point inward toward the center of the lens. Light tends to scatter when it hits the spoke-like opacities.

Posterior Subcapsular Cataract

Often referred to as a PSC, a posterior subcapsular cataract is an opacity that develops on the back surface of the lens, directly underneath the lens capsular bag that houses the lens.

This type of cataract causes light sensitivity, blurred near vision, and glare and halos around lights. They are more common in diabetic patients and patients who have taken steroids for extended periods of time.

Types of Cataracts by Origin

Eye doctors also classify cataracts according to their origin.

Age-related Cataract

Most cataracts develop as we age. Although signs can be seen as early as your 40s to 50s, cataracts usually do not become significant until the late 60s or 70s.

Secondary Cataracts

Cataracts can sometimes develop after undergoing eye surgery, such as surgery for glaucoma or retinal surgery. Patients with diabetes sometimes develop cataracts earlier than normal. Also, patients who are taking steroids for an extended period of time may develop cataracts.

Traumatic Cataract

Cataracts sometimes result from direct injury or trauma to the eye. Cataracts may develop immediately or years after an event that damages the eye. Traumatic cataracts often occur after blunt trauma to the eye or from exposure to certain chemicals.

Congenital Cataract

Some children are born with cataracts. In some cases, the inherited cataract is not significant enough to affect vision. If significant, however, the cataract should be removed in order to avoid vision problems, such as strabismus or amblyopia.

Radiation Cataract

Although rare, cataracts sometimes form after exposure to certain types of radiation. This type of cataract may be caused by exposure to ultraviolet light from the sun and other forms of radiation.