Cataracts

  • Medical Author:
    Andrew A. Dahl, MD, FACS

    Andrew A. Dahl, MD, is a board-certified ophthalmologist. Dr. Dahl's educational background includes a BA with Honors and Distinction from Wesleyan University, Middletown, CT, and an MD from Cornell University, where he was selected for Alpha Omega Alpha, the national medical honor society. He had an internal medical internship at the New York Hospital/Cornell Medical Center.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Cataracts Pictures Slideshow

Quick GuideCataracts Causes, Symptoms, Vision Tests and Surgery

Cataracts Causes, Symptoms, Vision Tests and Surgery

What are the different types of cataracts?

Cataracts can be classified by anatomical location within the lens, degree of clouding of the lens, or by the cause of the cataract.

The lens of the human eye is shaped and sized similar to an M&M candy. It has a front (anterior) part and a back (posterior) part. The central portion of the lens is called the lens nucleus, and the outer portion is called the lens capsule. Between the inner nucleus and the outer capsule is a portion of the lens called the cortex. Clouding of the lens can occur only in the nucleus, in which case the term "nuclear cataract" or "nuclear sclerosis" is used. If the clouding occurs in the lens cortex only, the cataract is termed a "cortical cataract." If the loss of clarity of the lens is primarily in or adjacent to the capsule, the term "subcapsular cataract" is used. The location of the clouding can also be defined as being anterior or posterior, central, or peripheral. Often the clouding of the lens may affect multiple portions of the lens. The most common type of cataract that is related to age is sometimes termed a "senile cataract." This type of cataract primarily involves the nucleus of the lens. Cataracts that develop in the posterior subcapsular area (in the rear region of the lens capsule) are more common in younger age groups.

Any degree of loss of the normal transparency of the lens is called a cataract. The cloudier the lens, the more advanced the degree of cataract. A cataract may be mild, moderate, or severe. It may be early or advanced. If the lens is totally opaque it is termed a "mature" cataract. Any cataract that is not opaque is therefore termed an "immature" cataract. Most mature cataracts are white in color.

What are risk factors for cataracts?

Advanced age is a significant risk factor for the development of cataracts. A family history for early development of cataracts, the presence of diabetes, tobacco use, and prolonged exposure to sunlight are also risk factors, as is trauma to the eye.

Medically Reviewed by a Doctor on 8/12/2016

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