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April 2009: Age-Related Macular Degeneration: A Summary

01 Apr 2009

Dr. Seenu Hariprasad is a board-certified ophthalmologist at Weiss Memorial Hospital. His specialties include diabetic retinopathy, age-related macular degeneration, macular holes and retinal detachment. Dr. Hariprasad is affiliated with Weiss Memorial Hospital through the University of Chicago Ophthalmology Clinic at Weiss.

Dr. Seenu Hariprasad
Ophthalmologist
University of Chicago Ophthalmology Clinic at Weiss
(773) 702-6110

The following summarizes an article published by Dr. Hariprasad in the Winter 2007 issue of Chicago Medicine magazine. It is reprinted with permission. View the complete article here.

Macular degeneration is characterized by a loss of function in the portion of the eye responsible for central vision. Because central vision makes possible the detailed sight required for activities such as reading, driving and recognizing faces, macular degeneration may significantly diminish the ability to function independently in individuals who suffer from this disease. While some forms of macular degeneration result from hereditary diseases, most cases occur as part of the aging process and are known as age-related macular degeneration (AMD).

AMD is a leading cause of blindness in people over age 55. AMD typically affects patients initially in one eye, with a high likelihood of it occurring over time in the second eye. Symptoms include blurred vision, difficulty seeing at a distance or doing detailed work—like sewing or reading fine print, blind spots developing in the middle of the field of vision, colors becoming hard to distinguish and distortion causing edges or lines to appear wavy.

In addition to aging, risk factors include:

  • Gender (women tend to be at greater risk than men)
  • Race (Caucasians are more likely to lose vision from AMD than African Americans)
  • Smoking
  • A family history of the disease
Approximately 15 million people in the United States have AMD, and more than 1.7 million Americans have the advanced form of AMD. Due to the aging baby boomer population, the National Eye Institute (NEI) estimates that advanced AMD prevalence will grow to 2.95 million by 2020. About 200,000 new cases of wet AMD are diagnosed each year in North America. Due to the rapid progression and severe, irreversible loss of central vision, early diagnosis and treatment is important for the successful management of wet AMD.

Types of AMD
There are two forms of AMD, dry (also called atrophic) and wet (neovascular). All cases of AMD begin as the dry form and, for unknown reasons, approximately 10 to 20 percent of these cases progress to the wet form. While both forms ultimately lead to loss of central vision, the degeneration occurs through different mechanisms and the course of the disease progression is different.

Dry AMD tends to progress more slowly than the wet form and is likely to cause severe loss of central vision or legal blindness in 15 percent to 20 percent of affected individuals. There are no treatments approved for dry AMD.

Approximately one in seven patients with dry AMD will develop the wet form. Wet AMD progresses more rapidly, and approximately 85 percent of affected individuals will advance to loss of central vision and be deemed legally blind.

In wet AMD, most damage to the retina occurs when new blood vessels begin to grow from the choroid up to the RPE and beneath the retina (a process known as choroidal neovascularization or ocular angiogenesis).

Diagnosis
Due to the rapid progression and severe, irreversible loss of central vision associated with wet AMD, early diagnosis and treatment is important for the successful management of the disease. A simple test, known as the Amsler grid, can be used to assess visual changes such as optical distortion or loss of vision.

The diagnosis of wet AMD generally requires optical coherence tomography, fluorescein angiography, or indocyanine green angiography.

Treatment options
Several recent studies have indicated a strong link between nutrition and the development of macular degeneration.

It has been scientifically demonstrated that people with diets high in fruits and vegetables (especially leafy green vegetables) have a lower incidence of macular degeneration. Studies have determined that a certain combination of vitamins can help slow the rate of progression from dry to wet macular degeneration in patients with certain forms of dry disease. The exact role of these vitamins is still controversial and a very large study is currently underway to address some of these issues.

Additionally, several drug injections and photodynamic therapies are approved in the United States for treatment of wet AMD (view the full article for specific drug names).

For more information
If you would like more information about AMD and treatment options or would like an appointment, contact Dr. Hariprasad’s office at (773) 702-6110 or retina@uchicago.edu.

Fact Sheet
Age Related Macular Degeneration