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Age-Related Macular Degeneration: Status of Research

March 1, 1997

Harold Varmus, M.D.
Director, NIH
March, 1997

The following document represents a 1997 report to Congress by the National Institutes of Health. For more current information on AMD, please visit the following links:
Age-Related Macular Degeneration: Information for Patients
Ongoing AMD Studies Supported by the NEI
Age-Related Eye Disease Study (AREDS)
Complications of Age-Related Macular Degeneration Prevention Trial (CAPT)
Submacular Surgery Trials (SST)
Table of Contents

Topic Page

Executive Summary
Age-Related Macular Degeneration
“Dry” AMD
“Wet” AMD
Status of Ongoing AMD Research
Low Vision and AMD
NEI Activities Supporting Low Vision Research
Executive Summary

The Senate Appropriations Committee, in its report accompanying the fiscal year 1997 Appropriations Bill, has requested a report from the National Eye Institute (NEI). The Committee has urged the NEI to “accelerate and encourage research in age-related macular degeneration (AMD),” and has asked NEI to provide a status report on research and prospects for the future.

AMD is a common eye disease of the macula, a tiny area in the retina that helps produce sharp, central vision required for “straight ahead” activities such as reading, sewing, and driving. A person with AMD loses this clear, central vision; in some cases, vision loss is rapid and dramatic. AMD is a leading cause of severe visual impairment and blindness in the United States. It is estimated that AMD already causes visual impairment in approximately 1.7 million of the 34 million Americans over age 65.

This report responds to the Committee’s request by outlining areas where NEI-supported scientists have focused their research efforts in AMD. Research in this area is a high priority of the Institute; in fiscal year 1997, the NEI is funding approximately $75 million of research in areas generally related to age-related macular degeneration. Of this amount, approximately $16 million is directly related to AMD. This $16 million figure represents a 333 percent increase from the $5 million spent in AMD research in fiscal year 1989.

Some examples of ongoing AMD research:

  • In a major clinical trial ongoing at 11 clinics nationwide, 4700 patients are being followed to identify risk factors for AMD.
  • The same clinical trial is measuring the effects of certain combinations of vitamins and minerals that may help prevent or slow the progress of AMD.

Other clinical studies are examining families with AMD to assess the role genetic and environmental factors may play in this complex chronic disease.

NEI scientists are continuing basic research efforts to identify genes that cause AMD and gain a better understanding of who is at greatest risk of developing the disease.

Researchers are exploring and developing treatment strategies, such as gene replacement, anti-angiogenesis factors, and pharmacological agents, to correct or delay the progression of the vision loss associated with AMD.

Groups of NEI-supported scientists have successfully transplanted healthy retinal pigment and photoreceptor cells into diseased retinas of laboratory animals. In addition to the above, the NEI recognizes that age-related macular degeneration is a leading cause of severe visual impairment in the United States, and the Institute is supporting research on low vision aids, devices, and other strategies for those who suffer from visual impairment. The NEI is also developing a new, low vision public education program as part of its National Eye Health Education Program. This new program will inform people about available low vision aids and services that can help them with their daily activities, such as reading, sewing, and driving, to improve their quality of life.

Measured by these exciting areas of research, the NEI is making great strides against blinding eye diseases and toward protecting and prolonging the eyesight of Americans.


In its report accompanying the Fiscal Year 1997 Appropriations Bill, the Senate Appropriations Committee stated:

“Age-related macular degeneration is the leading cause of severe visual impairment and blindness in the United States. The Institute has made great progress in this area through advances in cell and molecular biology. Additionally, genetics research and advances in the development of growth factors hold great promise for new treatments for this disease. The NEI is urged to accelerate and encourage research in this area, and to report the status of research in age-related macular degeneration and prospects for the future to the Committee.”

(Senate Report No. 104-368, Page 94)

The following report has been prepared by the National Eye Institute of the National Institutes of Health, Department of Health and Human Services in response to this request.


The National Eye Institute (NEI) administers Federal programs for the research on new and/or improved treatments for eye diseases and visual disorders. It is the Federal government’s lead agency for scientific research on the causes of blindness and the special health problems and requirements of individuals who are visually impaired.

Since its inception by Congress in 1968, NEI intramural and extramural researchers have conducted studies leading to breakthroughs in identifying causes and treating various diseases of the eye. These scientific advances have saved hundreds of thousands of people worldwide from vision loss and blindness and improved their quality of life.

Age-Related Macular Degeneration

An eye disease causing increasing concern among health professionals is age-related macular degeneration (AMD), a common eye disease of the macula, a tiny area in the retina that helps produce sharp, central vision required for “straight ahead” activities such as reading, sewing, and driving. A person with AMD loses this clear, central vision. It is estimated that AMD already causes visual impairment in approximately 1.7 million of the 34 million Americans over age 65. Since Fiscal Year 1989, the NEI has devoted an increasing percentage of its annual appropriation to AMD research.

In some cases, AMD advances so slowly that people notice little effect on their vision; however, in others, the disease progresses faster and may lead to a loss of vision in one or both eyes.

AMD occurs in two forms — a “dry” form and a “wet” form.

  • Dry AMD. Scientists are uncertain of the causes of “dry” AMD, in which there is a slow breakdown of light-sensing cells in the macula, subsequently reducing central vision. About 90 percent of people with AMD have this type of the disease. Unfortunately, there is as yet no treatment for “dry” AMD. It has been suggested that supplemental vitamins and minerals may slow the progress of the disease. However, more research needs to be conducted into finding ways to prevent, slow, or cure “dry” AMD.
  • Wet AMD. As “dry” AMD worsens, new, fragile blood vessels grow beneath the macula. These new blood vessels often leak blood and fluid, causing rapid damage to the macula and quickly leading to loss of central vision. although only 10 percent of those with AMD have this type of the disease, “wet” AMD accounts for 90 percent of all blindness resulting from AMD. Research supported by the NEI was instrumental in the development of laser surgery to treat some cases of the “wet” form of AMD. This treatment, performed in a doctor’s office or eye clinic, involves aiming a strong light beam toward the new blood vessels and destroying them, preventing further loss of vision. However, it should be noted that only about 15 percent of patients with the “wet” form of AMD are eligible for laser surgery because the new blood vessels may have advanced too close to the area of the macula on which the visual image is focused. Despite laser treatment, the disease and loss of vision may progress, and once vision is lost, it cannot be restored.

The phrase “age-related” is associated with macular degeneration because data show that the risk of AMD dramatically increases after age 60. This disease is the leading cause of severe visual impairment and blindness in Americans 60 years of age and older.

As “baby boomers” age and a higher percentage of Americans reach age 60, more older people may become blind from AMD than from glaucoma and diabetic retinopathy combined. In addition to the obvious quality of life issues faced by those with AMD, effective treatment of even 25 percent of all cases could lead to significant savings to society and decreases in the number of Social Security and other disability payments. These savings would far outweigh the costs of clinical management and treatment.

Race plays a key role in a person’s susceptibility to AMD — whites are much more likely to lose vision from AMD than blacks. Women tend to be at slightly greater risk then men. Heredity is also a factor.

What is special about the macula that renders it susceptible to degeneration? Are these changes due to genetic, immunologic, or environmental factors? Finding causes of this disease and developing safe and more effective preventative measures and treatments is a priority at the NEI. We intend to spend approximately $75 million dollars — 22 percent of NEI’s Fiscal Year 1997 budget — on all macular degeneration-related research. Of this $75 million, approximately $16 million is specifically targeted to researching causes, prevention, and treatment of AMD. This $16 million figure represents a 333 percent increase from the $5 million spent in AMD research in fiscal year 1989.

Status of Ongoing AMD Research

The NEI is currently funding a number of studies to learn what causes AMD and how it can be prevented or treated more successfully.

Through the Age-Related Eye Disease Study, researchers at 11 clinical centers around the country are assessing the aging process, potential risk factors, and quality of life of 4700 patients. These characteristics may be associated with the development of AMD. Once such studies have helped us to determine how macular degeneration develops, we might be able to change its course; when we know for certain what risk factors contribute to development of the disease, we can caution patients to avoid them.

The Age-Related Eye Disease Study also includes clinical trials that will help determine the effects of certain vitamins and minerals in preventing or slowing the progress of AMD. In particular, researchers are closely examining whether vitamins C and E, beta-carotene, and/or zinc can provide the macula with greater protection, thereby preventing or slowing progression of the disease. If dietary supplements prove effective, it would have a huge impact on AMD treatment and reduce the need for low vision services and devices for older Americans. It should be noted that on occasion, seemingly benign nutrients such as vitamins and minerals can be harmful when taken inappropriately, especially vitamins that accumulate in body fat. When the Age-Related Eye Disease Study is completed within the next five years, we will know whether any of these vitamin and mineral combinations are both effective and safe therapy for macular degeneration.

A five-year study begun in 1996 is evaluating genetic and environmental factors related to AMD and examining an underlying hypothesis that genetic factors play a significant role in this complex chronic disease. Entitled “Etiologic Studies of Age-Related Macular Degeneration,” participating families include those with both a single case of documented AMD and those where at least two living siblings (or a parent) have documented AMD.

Other approaches to solving the problem of AMD include laboratory, or basic, research. This research includes studies of genetic factors to gauge the role of heredity in the development of AMD. For example, scientists have identified the defective genes involved in two other types of inherited macular degeneration; these inherited diseases share similarities with AMD. In addition, genes associated with several other forms of macular degeneration have been localized to specific chromosomes. Knowing the genes associated with these diseases should enable researchers to determine the relationship of the gene product to the degenerative process.

NEI scientists are also trying to identify genes that could help rescue the retina; this strategy may help to prevent much of the visual loss from later stages of AMD. Researchers are exploring the effects that gene replacement may have on the treatment of retinal degeneration. Scientists have already successfully placed genes into the retina of laboratory animals, and clinical trials in humans are in the planning phase. Treatment strategies under development include anti-angiogenesis factors and pharmacological agents.

Replacing diseased retinal cells with healthy ones is a promising area of research. NEI scientists are determining whether retinal cell transplants are useful to treat the retinal degeneration caused by AMD. Groups of NEI-supported scientists have successfully transplanted healthy retinal pigment and photoreceptor cells into diseased retinas of laboratory animals.

Animal models have been developed which mimic the condition of blood vessel ingrowth and scarring seen in the “wet” form of the disease. These models are useful in screening therapies for this form of AMD.

Clinical trials are beginning to study the effects of various anti-inflammatory therapies on the development and progression of the previously untreatable “wet” forms of AMD.

The NEI also sponsored a workshop that led to shared research ideas and consideration of the future direction of AMD research. This workshop, held last June, brought together academicians, clinicians, and representatives from biotechnology companies, all of whom were knowledgeable in growth factor cell biology. The discussion centered around the potential use of neurotrophins, or biological survival factors, to delay clinical manifestations of retinal cell degeneration in AMD and other eye diseases.

Low Vision and AMD

In addition to being a leading cause of blindness in the United States, AMD is also a leading cause of low vision, broadly defined as a visual impairment interfering with an individual’s ability to perform activities of daily living. There are approximately three million Americans who suffer from visual conditions that are not correctable by standard glasses or contact lenses. People with low vision often cannot perform daily routine activities, such as reading the newspaper, preparing meals, or recognizing faces of friends. The graying of our population will be a key factor in the increasing rates of low vision and have a significant effect on our health care system.

The inability to see well affects functional capabilities and social interactions and can lead to a loss of independence. However, while there is nothing medically that can be done for patients with low vision, their quality of life can be greatly improved. Many low vision services and devices are available to help patients maintain their independence; some can even learn to drive again.

Generally, low vision devices fall into two categories: optical and non-optical. Optical devices use lenses or combinations of lenses to provide magnification. These include such aids as magnifying spectacles, hand-held magnifiers, stand magnifiers, computer monitors with large type, and closed-circuit televisions. Non-optical devices include large-print reading materials (books, newspapers), check writing guides, and high contrast watch dials. Also included in this category are auditory aids, such as talking computers.

NEI Activities Supporting Low Vision Research
As the leading source of vision research funds in the United States, the NEI is committed to furthering progress in the area of low vision research. During 1996, NEI-supported 18 extramural research projects related to low vision, with a total funding of over $4 million.

Examples of NEI-supported research include projects designed to:

  • Measure the visual requirements of reading for individuals with normal and low vision. Among other information, this research will provide improved understanding of the sensory constraints of normal reading.
  • Develop a set of techniques that will determine the potential benefits of cataract surgery in patients with AMD. It is estimated that over half of the people with AMD also have cataracts. Cataract surgery is often not performed because the benefits of the surgery may be minimal due to the presence of AMD. The study also will assess the combined effects of cataracts and AMD on reading, face recognition, other everyday visual activities, and health-related quality of life issues.

Our investment in high quality clinical research has little real benefit unless the results and recommendations from such studies are widely and suitably incorporated into patient care. Results of low vision research must be disseminated to the public so people can take more proactive approaches to ensure their own health. One way this happens is through the National Eye Health Education Program (NEHEP), which is developing an education program aimed at addressing the needs of people with low vision. This new program will increase public awareness about the impact of low vision on daily living. Since fewer than 25 percent of patients who might benefit from low vision services actually receive such care, the NEHEP’s low vision program will play a key role in informing Americans about the use of optical and non-optical low vision devices and services.

NEI’s research program also helps inventors with ideas on low vision aids develop those ideas for the marketplace. Inventors have few resources available allowing them to develop products that help people suffering from low vision. NEI’s Small Business Innovation Research Grants Program gives inventors the opportunity to see their ideas turned into reality. For example, through this program, telescopic systems were developed that help those with low vision perform common tasks, such as walking down the street or reading signs. Another idea, a system called “Outspoken,” magnifies text on a computer screen, making it easier for people with low vision to read. This product was recognized by the Smithsonian Institution for its unique way of using technology for the common good. A sister program, called the Small Business Technology Transfer Grant, encourages inventors in universities or research centers to form partnerships with small businesses. Between both programs, in Fiscal Year 1997 NEI expects to fund approximately 10 projects in the area of low vision research.


The National Eye Institute is making strides toward researching the cause of and developing treatments for age-related macular degeneration while ensuring judicious use of Federal research dollars. The various areas of NEI-supported research, including gene identification, gene replacement therapy, vitamin and mineral dietary supplementation, retinal cell transplantation, and pharmaceutical intervention, hold promise as scientists also look to identify genes that cause AMD and develop treatments to prevent the disease or slow its progression. Efforts in the area of low vision research are gathering momentum. The NEI will continue to devote a significant portion of its annual budget to support research aimed toward learning more about this debilitating disease that affects the lives of millions of Americans.