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Healio
ByNeil M. Bressler, MD
February 01, 2006
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New treatments in 2006 for patients with AMD

ByNeil M. Bressler, MD

Age-related macular degeneration is the leading cause of vision loss in people older than 55 years. Patients associate blindness as resulting in a quality of life worse than that associated with congestive heart failure. There is no cure for AMD; until anti-vascular endothelial growth factor treatments were available, treatments have only decreased the risk of vision loss. The vitamin supplements used in the Age-Related Eye Disease Study have been shown to reduce the risk of advanced AMD. However, these supplements do not improve vision. Thus, more effective treatments are needed to better target AMD and preserve patients’ vision and quality of life.

History of AMD treatment

In 1980, treatment for patients with choroidal neovascular lesions involving the center of the fovea was unavailable. In 1981, the thermal laser was introduced and reduced the risk of vision loss in patients with extrafoveal CNV. The thermal laser trials provided the methodology for the photodynamic therapy trials, leading to the use of PDT in 1999. In 2001, ophthalmologists offered dietary supplements to patients to help prevent the onset of advanced AMD. In 2004, the antiangiogenic drug pegaptanib was approved by the Food and Drug Administration. Pegaptanib helps reduce the risk of vision loss from advanced AMD by inhibiting vascular endothelial growth factor (VEGF) growth.

According to the Year 2000 Census Bureau, 59 million people were older than 55 years in the United States. Five million of these people had intermediate AMD (usually large drusen) in one eye, 2.25 million had intermediate AMD in both eyes, and 1 million had advanced AMD in one eye, with the other eye at risk. (Intermediate AMD occurs when a patient has drusen.) Eight million people, then, may develop advanced AMD and have intermediate AMD in one or both eyes. In 2005, another antiangiogenic drug, ranibizumab (currently under investigation), demonstrated an increased chance of vision improvement with little chance of severe vision loss. In the next 5 years, the use of a dietary supplement such as that used in the Age-Related Eye Disease Study (AREDS) by the 8 million people in the U.S. with intermediate AMD could prevent vision loss in 300,000 out of 1.3 million people with advanced AMD. In 2006, with the use of ranibizumab, ophthalmologists have an increased chance of improving vision in the 1 million patients who may develop neovascular AMD.

Impact of AMD

Intermediate AMD involves an abnormal thickening of the basement membrane of the pigment epithelium and the formation of large drusen. This abnormal thickening is seen as yellow spots in the center of the retina.

Although intermediate AMD affects vision in only a small number of patients, patients with intermediate AMD are at risk for developing advanced AMD. Approximately 6% of the 5 million patients who have AMD in one eye have large drusen in one eye, 26% of the 2.25 million people who have intermediate AMD in both eyes have large drusen in both eyes and 43% of the 1 million people who have advanced AMD in one eye will develop advanced AMD in the second eye over 5 years. If no treatment for intermediate AMD were available, then 1.3 million people would develop advanced AMD in the next 5 years (Figure). These data are a major public health issue because AMD impacts patients’ vision and quality of life.

Estimated Progression Rate

Figure

Figure. Without effective treatment, more than 1 million people will develop advanced AMD in the next 5 years.2

Source: Bressler N.M.

According to AREDS, dietary supplements can be helpful for patients with intermediate AMD.

Taking 500 mg of vitamin C, 400 IU of vitamin E, 15 mg of beta-carotene and 80 mg of zinc combined with 2 mg of cupric oxide daily can reduce the risk of developing advanced AMD within 5 years by 20%. In AREDS, patients with intermediate AMD who received sham treatment had a 28% probability of developing advanced AMD within 5 years. Dietary supplements reduced the risk to 20%.

We estimated that if the 8 million people who took dietary supplements used the dosages that the patients in AREDS used, 300,000 of them would prevent the development of advanced AMD during the next 5 years. This result has encouraged many ophthalmologists to consider recommending these dietary supplements to patients with intermediate AMD. However, 1 million patients will develop advanced AMD during the next 5 years even if they take dietary supplements. At least two-thirds of these patients will develop neovascular AMD. Advanced AMD, CNV and central geographic atrophy, can limit patients’ ability to read, tell time, recognize faces and drive. Thus, ophthalmologists are concentrating on early diagnosis and new treatments for these patients.

More research needed on AMD treatment

Because AREDS-formulated vitamins will not prevent vision loss in everyone with the intermediate stage of AMD, increased research is crucial to develop new treatments. By helping patients reduce their risk of disease progression, new treatments will reduce the impact of AMD on patients’ quality of life. One way of assessing the impact of AMD is to measure how patients with neovascular AMD grade their overall health on a preference value scale. This preference value is measured on a scale of 0 to 100, with 100 representing perfect health and perfect vision, to a value of 0 representing death. The Submacular Surgery Trials (SST) showed that patients who have subfoveal CNV score their state of health as approximately 65. Using similar methods, patients associate having congestive heart failure with a score of 79 or 80.

Because AREDS will not prevent vision loss in everyone with the intermediate stage of AMD, increased research is crucial to develop new treatments.

— Neil M. Bressler, MD

A report in the Archives of Ophthalmology showed the respondents who had subfoveal CNV in both eyes to have a preference value around 55, showing them to have a state of health equal to that of patients with chronic renal failure on home dialysis. Patients who had complete blindness reported preference value scores between 30 and 40.

No treatment is available for patients who develop advanced AMD with vision loss and geographic atrophy in the fovea. The basement membrane thickens, drusen form and atrophy of the retinal pigment epithelium, choriocapillaris and photoreceptors develops. Also, no treatment is available for patients with lesions that are predominantly scarred.

AMD is one of the leading causes of vision loss in patients older than 55 years. Patients associate blindness with a lower quality of life than that associated with congestive heart failure and other life-threatening illnesses. PDT, dietary supplements and pegaptanib offer limited success.

The future of AMD treatment indicates greater benefit with some antiangiogenic drugs. Ranibizumab has promise to be more effective than PDT and pegaptanib because it increases the chance of vision improvement and few patients develop further vision loss in selected cases studied. Thus, ranibizumab holds promise as an effective treatment in years to come.

References

  1. Age-related eye disease study (AREDS). National Eye Institute website. Available at: http://www.nei.nih.gov/amd/index.asp. Accessed January 4, 2006.
  2. Age-related eye disease study (AREDS). Report No. 11. National Eye Institute website. Available at: http://www.nei.nih.gov/amd/index.asp. Accessed January 4, 2006.
  3. Age-related eye disease study (AREDS). Report No. 8. National Eye Institute website. Available at: http://www.nei.nih.gov/amd/index.asp. Accessed January 4, 2006.
  4. Submacular Surgery Trials. Report No. 6. ClinicalTrials.gov, a service of the US National Institutes of Health. Available at: http://www.clinicaltrials.gov/ct/show. Accessed January 4, 2006.
  5. Brown GC, Sharma S, Brown MM, Kistler J. Utility values and age-related macular degeneration. Arch Ophthalmol. 2000;118:47-51.