CBC News
An Ottawa company is developing computerized glasses that help people with severe visual impairments see — as well as zoom in on and replay what they saw with the press of a button.
The company, eSight Corp., received a $500,000 grant from the Ontario government this week to develop its evSpex product as part of a special $4.5 million fund to help 10 start-up companies bring products to market.
The device, which resembles a pair of large sunglasses, has a high-resolution camera on the outside and tiny LCD screens on the inside that project images to the wearer's eyes.
Before the image is projected, it's custom-processed by a tiny computer, said company president Rob Hilkes.
"So that when it's presented to a person who has diseased eyes … it's presented to the pieces of their vision that are most functional," he added.
Réjean Munger, a senior scientist at the Ottawa Hospital Research Institute who helped develop the glasses, said that can help people with a variety of diseases.
"We can take advantage of every bit of vision they have," he said.
The company hopes to start commercial production next year.
Sister of company chairman inspiration for glasses
Anne Lewis, who is legally blind as a result of Stargardt's disease, has been testing the prototype and is very excited about it.
"I see this product as a gift; I truly do," she said at the news conference announcing the funding.
Lewis is the sister of Conrad Lewis, eSight's chairman and one of the company's founders, and her disability was the inspiration for the glasses.
Stardgardt's disease is a form of macular degeneration that has destroyed Anne Lewis's sight except for her peripheral vision.
"It's like looking at a bubble and the inside of the bubble is black, the outside is clear," she said.
Lewis said using the glasses will allow her to read body language in meetings at work, stand on her deck and see flowers blooming, navigate shopping malls and flag down the right bus.
Unlike other products she has tried, it works even while she is moving.
The product is expected to be able to help people with age-related macular degeneration, diabetic retinopathy, glaucoma and retinitis pigmentosa.
Users can record, zoom
Because the device is essentially recording a loop of video at all times, it will include special functions that people with normal vision don't have. For example, the user can save the last 10 seconds of what they saw at the press of a button so they can have another look at something that went by too quickly. The video can also be viewed later on a DVD player or computer. In addition, they could zoom in on certain things in their field of view.
Hilkes said the features are available because the "inherent guts" of the device are a computer.
"Once you pack a lot of electronics into a system like this, then creative people start to think of all kinds of ways that you could use it," he said.
In the future, the company hopes to market the technology to people with normal vision as wearable binoculars, night vision goggles or video gaming devices.
For more information go to www.maculardegenerationassociation.org
Friday, September 18, 2009
Wednesday, September 9, 2009
Increase Your Omega-3s
Within the polyunsaturated fat category, there are two important subclasses of fatty acids: omega-3s and omega-6s. Vegetable oils are rich in omega-6 fatty acids, and most Americans unknowingly get plenty of them in the diet. On the other hand, omega-3 fatty acids, which are found in fish and shellfish, tofu, flax, nuts and canola and soybean oils, are generally lacking in our diets.
Omega-3s appear to have a positive effect on heart rhythm and according to one recent study, may even reduce the incidence of the most common type of stroke. In fact, on the basis of the current research, the U.S. Food and Drug Administration approved the use of a qualified health claim for dietary supplements of omega-3 fatty acids relating them to a reduced risk of heart disease.
Another intriguing area of research on omega-3 fatty acids pertains to their role in brain and visual function, as some research suggests they may have a role in preventing macular degeneration, a common form of blindness.
Continuing research involves the role of omega-3 fatty acids and the immune system, and suggests a positive influence on rheumatoid arthritis, asthma, lupus, kidney disease and cancer, as well as promising research at the National Institutes of Health on depression.
For more information go to: www.maculardegenerationassociation.org
Omega-3s appear to have a positive effect on heart rhythm and according to one recent study, may even reduce the incidence of the most common type of stroke. In fact, on the basis of the current research, the U.S. Food and Drug Administration approved the use of a qualified health claim for dietary supplements of omega-3 fatty acids relating them to a reduced risk of heart disease.
Another intriguing area of research on omega-3 fatty acids pertains to their role in brain and visual function, as some research suggests they may have a role in preventing macular degeneration, a common form of blindness.
Continuing research involves the role of omega-3 fatty acids and the immune system, and suggests a positive influence on rheumatoid arthritis, asthma, lupus, kidney disease and cancer, as well as promising research at the National Institutes of Health on depression.
For more information go to: www.maculardegenerationassociation.org
Wednesday, September 2, 2009
Palladium-103 plaque radiation therapy for macular degeneration: results of a 7 year study
Aim: To report 7 year results of ophthalmic plaque radiotherapy for exudative macular degeneration.
Methods: In a phase I clinical trial, 30 patients (31 eyes) were treated with ophthalmic plaque irradiation for subfoveal exudative macular degeneration. Radiation was delivered to a mean 2 mm from the inner sclera (range 1.2–2.4) prescription point calculated along the central axis of the plaque. The mean prescription dose was 17.62 Gy (range 12.5–24) delivered over 34 hours (range 18–65). Early Treatment Diabetic Retinopathy Study (ETDRS) type standardised visual acuity determinations, ophthalmic examinations, and angiography were performed before and after treatment. Clinical evaluations were performed in a non-randomised and unmasked fashion.
Results: At 33.3 months (range 3–4), 17 of 31 (55%) eyes had lost 3 or more lines of vision on the ETDRS chart, five (16%) had improved 3 or more lines, and the remaining nine (29%) were within 2 lines of their pretreatment visual acuity measurement. Overall, 45% of patients were within or improved more than 2 lines of their initial visual acuity. Five eyes developed macular scars, eight developed subsequent neovascularisation or haemorrhage, and three progressed through therapy. Two patients were lost to follow up. The most common finding of patients followed for 6 or more months (n = 18 of 29 (62%)) was regression or stabilisation of the exudative process. No radiation retinopathy, optic neuropathy, or cataracts could be attributed to irradiation.
Conclusion: Ophthalmic plaque radiation can be used to treat exudative macular degeneration. At the dose and dose rates employed, most patients experienced decreased exudation or stabilisation of their maculas. No sight limiting radiation complications were noted during 7 year follow up. Owing to the variable natural course of this disease, a prospective randomised clinical trial should be performed to evaluate the efficacy of plaque radiation therapy for exudative macular degeneration.
Methods: In a phase I clinical trial, 30 patients (31 eyes) were treated with ophthalmic plaque irradiation for subfoveal exudative macular degeneration. Radiation was delivered to a mean 2 mm from the inner sclera (range 1.2–2.4) prescription point calculated along the central axis of the plaque. The mean prescription dose was 17.62 Gy (range 12.5–24) delivered over 34 hours (range 18–65). Early Treatment Diabetic Retinopathy Study (ETDRS) type standardised visual acuity determinations, ophthalmic examinations, and angiography were performed before and after treatment. Clinical evaluations were performed in a non-randomised and unmasked fashion.
Results: At 33.3 months (range 3–4), 17 of 31 (55%) eyes had lost 3 or more lines of vision on the ETDRS chart, five (16%) had improved 3 or more lines, and the remaining nine (29%) were within 2 lines of their pretreatment visual acuity measurement. Overall, 45% of patients were within or improved more than 2 lines of their initial visual acuity. Five eyes developed macular scars, eight developed subsequent neovascularisation or haemorrhage, and three progressed through therapy. Two patients were lost to follow up. The most common finding of patients followed for 6 or more months (n = 18 of 29 (62%)) was regression or stabilisation of the exudative process. No radiation retinopathy, optic neuropathy, or cataracts could be attributed to irradiation.
Conclusion: Ophthalmic plaque radiation can be used to treat exudative macular degeneration. At the dose and dose rates employed, most patients experienced decreased exudation or stabilisation of their maculas. No sight limiting radiation complications were noted during 7 year follow up. Owing to the variable natural course of this disease, a prospective randomised clinical trial should be performed to evaluate the efficacy of plaque radiation therapy for exudative macular degeneration.
Friday, August 28, 2009
Researchers Grow Eye Cells From Skin Cells
Researchers have succeeded in growing light-sensing eye cells from human skin cells, opening the possibility of restoring sight to patients blinded by certain diseases.
Researchers at the University of Wisconsin have grown retinal cells from skin cells, a development that could be used to treat degenerative eye diseases.
A number of genetic disorders involve the degeneration of the retina, the light-sensitive cells at the back of the eye. The disorders cause the cells to die, and vision is gradually lost, resulting in blindness.
The researchers manipulated human skin cells to act like embryonic stem cells, which can be coaxed to grow into any tissue in the body. The development suggests that doctors may someday be able to repair damage to the retina with new cells generated from the patient's own skin.
Lead researcher David Gamm, a professor of ophthalmology and visual sciences at the University of Wisconsin, says his research could benefit people with macular degeneration and retinitis pigmentosa. In both diseases, the visual field gradually narrows, eventually leading to blindness.
"In particular these diseases are quite devastating to the patients who are affected by them," he said. "They rob them of their vision either when they are younger in the case of retinitis pigmentosa or when they are older in the case when they are older in the case of macular degeneration. And there are no cures and very few if any treatments for them. So it is a big need, especially from the macular degeneration standpoint, as the population ages."
An estimated one million people worldwide are affected by macular degeneration alone.
Gamm says the laboratory process of creating human retinal cells helps researchers better understand how eyes develop, so diseases that lead to vision loss may someday be treated or even cured with retinal stem cells.
The development could also further research on genetic eye conditions. For example, using skin cells from a patient with retinitis pigmintosa researchers could create retinal cells with the defective gene and subject them to various potential drugs for treating or curing the condition.
Gamm says the same technique could help scientists find treatments for other genetic diseases, not just eye disorders.
"Now we could take theoretically any human disease, especially those that have specific gene defects underlying them, and produce cell types of interest in those diseases and test them directly for the efficacy of various drugs or how in fact those cells die in disease," he added.
The study on the development of eye cells is published this week in the journal Proceedings of the National Academy of Sciences.
By Jessica Berman
Washington
Researchers at the University of Wisconsin have grown retinal cells from skin cells, a development that could be used to treat degenerative eye diseases.
A number of genetic disorders involve the degeneration of the retina, the light-sensitive cells at the back of the eye. The disorders cause the cells to die, and vision is gradually lost, resulting in blindness.
The researchers manipulated human skin cells to act like embryonic stem cells, which can be coaxed to grow into any tissue in the body. The development suggests that doctors may someday be able to repair damage to the retina with new cells generated from the patient's own skin.
Lead researcher David Gamm, a professor of ophthalmology and visual sciences at the University of Wisconsin, says his research could benefit people with macular degeneration and retinitis pigmentosa. In both diseases, the visual field gradually narrows, eventually leading to blindness.
"In particular these diseases are quite devastating to the patients who are affected by them," he said. "They rob them of their vision either when they are younger in the case of retinitis pigmentosa or when they are older in the case when they are older in the case of macular degeneration. And there are no cures and very few if any treatments for them. So it is a big need, especially from the macular degeneration standpoint, as the population ages."
An estimated one million people worldwide are affected by macular degeneration alone.
Gamm says the laboratory process of creating human retinal cells helps researchers better understand how eyes develop, so diseases that lead to vision loss may someday be treated or even cured with retinal stem cells.
The development could also further research on genetic eye conditions. For example, using skin cells from a patient with retinitis pigmintosa researchers could create retinal cells with the defective gene and subject them to various potential drugs for treating or curing the condition.
Gamm says the same technique could help scientists find treatments for other genetic diseases, not just eye disorders.
"Now we could take theoretically any human disease, especially those that have specific gene defects underlying them, and produce cell types of interest in those diseases and test them directly for the efficacy of various drugs or how in fact those cells die in disease," he added.
The study on the development of eye cells is published this week in the journal Proceedings of the National Academy of Sciences.
By Jessica Berman
Washington
Tuesday, August 4, 2009
An Overview of Macular Degeneration Research
Doctors and scientists are currently conducting macular degeneration research. Macular degeneration research studies are designed to answer important questions and to find out whether new approaches are safe and effective. This research already has led to many advances, and researchers continue to search for more effective methods for dealing with macular degeneration.
Current Areas of Focus in Macular Degeneration Research
A number of macular degeneration research studies are being conducted to learn what causes macular degeneration and how it can be better treated.
One macular degeneration research study is also evaluating the effects of certain vitamins and minerals in preventing or slowing the progress of the disease.
At the same time, scientists studying macular degeneration are trying to learn more about how the cells in the retina work. This knowledge will allow them one day to pinpoint the causes of macular degeneration and come up with ways to prevent it.
Other areas of current research include:
* Studying the possibility of transplanting healthy cells into a diseased retina
* Evaluating families with a history of macular degeneration to understand genetic and hereditary factors that may cause the disease
* Looking at certain anti-inflammatory treatments for the wet form of macular degeneration.
This macular degeneration research should provide better ways to detect, treat, and prevent vision loss in people with the disease.
for more information www.maculardegenerationassociation.org
Current Areas of Focus in Macular Degeneration Research
A number of macular degeneration research studies are being conducted to learn what causes macular degeneration and how it can be better treated.
One macular degeneration research study is also evaluating the effects of certain vitamins and minerals in preventing or slowing the progress of the disease.
At the same time, scientists studying macular degeneration are trying to learn more about how the cells in the retina work. This knowledge will allow them one day to pinpoint the causes of macular degeneration and come up with ways to prevent it.
Other areas of current research include:
* Studying the possibility of transplanting healthy cells into a diseased retina
* Evaluating families with a history of macular degeneration to understand genetic and hereditary factors that may cause the disease
* Looking at certain anti-inflammatory treatments for the wet form of macular degeneration.
This macular degeneration research should provide better ways to detect, treat, and prevent vision loss in people with the disease.
for more information www.maculardegenerationassociation.org
Sunday, July 12, 2009
Novel Biomarker for Age-Related Macular Degeneration
A team of researchers at the University of Kentucky has discovered a biological marker for neovascular age-related macular degeneration (AMD), the leading cause of blindness in older adults. The scientists say the biomarker shows strong potential as a means for both the early detection of the disease and for preventive treatment.
Saturday, June 6, 2009
The Aging Eye: Researchers Aim To Stop the Clock
By JANE E. BRODY
AGING Americans expect more from their eyes these days than ever before. People in their 70's and 80's want to be able to drive, play cards, recognize people on the street, travel with their grandchildren, take advantage of senior discounts in the movies and read the books they missed while working full time.
But eyes have a way of aging that can render such expectations unrealistic. Far worse than the loss of visual acuity that prompts most middle-aged people to resort to magnifying lenses are sight-robbing diseases like glaucoma, cataracts, age-related macular degeneration, diabetic retinopathy and other retinal disorders that afflict tens of millions of Americans, usually after age 50.
The incidence of such potentially blinding disorders is increasing rapidly as the number of older people grows. Experts predict, for example, that by the year 2030, 6.3 million older Americans will develop macular degeneration, up from 1.7 million in 1995. It is a still-irreversible disorder that robs people of the central vision needed to drive, read, watch television, recognize faces, play cards or do any fine work. If Grandma Moses had had macular degeneration, her artistic talents would never have been noticed.
Fortunately, research is progressing on a number of promising new treatments, including low doses of radiation, and a combination of lasers and light-activated chemicals, both of which are used for some particularly hard-to-treat forms of macular degeneration. Other research is concentrating on how to stop toxins that damage the eye in glaucoma, and the genetics of several different eye diseases.
''Older Americans today expect to enjoy their retirement with the same visual capacity that they had in their younger years,'' said Dr. Harold Spalter, professor of ophthalmology at Columbia-Presbyterian Medical Center in New York. But, alas, as was apparent at a four-day seminar that Dr. Spalter chaired here last month, researchers are still a long way from knowing how to reverse most blinding eye disorders.
Still, major progress in understanding and treating these conditions -- and perhaps detecting them early enough to blunt their effects -- was evident at the seminar, organized by Research to Prevent Blindness, a New York-based voluntary organization. Unfortunately, though, many elderly Americans cannot afford the early detection procedures described at the seminar because Medicare and many other insurance programs do not cover such preventive measures.
For example, while insurance companies would routinely cover a visual field examination for a patient who already has glaucoma, most would not pay for this test for a person who has not yet experienced vision loss, when the disease process might be stopped without lasting vision damage.
Furthermore, an ongoing study of 2,520 men and women aged 65 to 84 in Salisbury, Md., has revealed that the usual eye chart test for visual acuity is inadequate to assess vision losses that interfere with the ability of elderly people to get around on their own, perform tasks of daily living and avoid accidents that can result in serious or fatal injuries. Rather, Dr. Sheila West, professor of ophthalmology at Johns Hopkins Medical Institutions, reported that tests for contrast sensitivity -- the ability to distinguish, say, a step from the one below it -- are more revealing of functional disability in older people.
''We have found that loss of contrast sensitivity is as important as arthritis and heart failure in determining loss of mobility in the aged,'' Dr. West said. She traced this loss to ''nonspecific retinal changes'' and the beginnings of cataracts, a gradual clouding of the lens of the eye that eventually obscures vision. However, early-stage cataracts are rarely recognized by those who have them and are often dismissed as inconsequential by eye doctors.
Sunlight, Dr. West said, is a major factor in the formation of cataracts, and the damage is cumulative. By assessing the exposure of study participants to sunlight, Dr. West and colleagues determined that for every 1 percent increase in exposure to ultraviolet-B light, the risk of developing cataracts rose by 10 percent.
''There is no threshold for sun-related damage, the dosage is cumulative and no group is immune to it,'' Dr. West said the study showed. She recommended that when out of doors, everyone -- starting in childhood -- should wear lenses that block ultraviolet light and a cap with a brim that shades the eyes.
Dr. M. Cristina Leske, head of preventive medicine at University Medical Center in Stony Brook, N.Y., and associates, identified other risk factors for cataracts. Through a five-year study of 764 patients, they found that Caucasians are three times as likely as blacks to develop cataracts. Those who take the gout medicine allopurinol face more than a two-fold increase in risk, and smokers have a 60 percent increase.
On the other hand, certain nutrients appear protective. The risk was 30 percent lower among those who took multivitamin-mineral supplements and nearly 60 percent lower among those who took a vitamin E supplement, a finding that is now being tested in a clinical trial sponsored by the National Eye Institute. Still another study of 247 women aged 56 to 71 conducted at Tufts University in Boston found that taking vitamin C supplements for more than 10 years reduced the risk of early cataracts by 77 percent and the risk of moderately advanced cataracts by 83 percent.
But while cataracts can usually be treated very successfully by surgically removing the damaged lens and replacing it with a synthetic lens implant, age-related macular degeneration, the leading cause of legal blindness in the elderly, has yet to yield to an effective treatment. Macular degeneration involves progressive damage to the cells in the center of the retina that are responsible for straight-ahead vision.
Early cases are often treated with lasers, which have the unfortunate side effect of destroying normal retinal cells as well as the damaged areas beneath them. Furthermore, after laser treatment, the vision-damaging tissue often grows back.
Dr. Dennis M. Marcus, an ophthalmologist at the Medical College of Georgia in Augusta, said that laser therapy usually cannot be used for the most severe form of the disease -- so-called wet macular degeneration, which involves the growth of leaky blood vessels beneath the central retina. Instead, he and his colleagues are testing low-dose radiation to destroy the blood vessels but spare the normal retinal cells. Thus far, 100 patients have been treated in a clinical trial that will eventually involve 500 people with wet macular degeneration. While it is too soon to evaluate the effectiveness of the treatment, Dr. Marcus said that he has seen no radiation-induced complications.
Another clinical study is testing a technique called photodynamic therapy. It starts with the intravenous administration of a photosensitive dye that collects in the damaging blood vessels that are growing beneath the retina. The eye is then exposed to laser light that activates the dye, destroying those vessels only. Dr. Joan W. Miller, an ophthalmologist at the Massachusetts Eye and Ear Infirmary, said that preliminary studies showed that the technique effectively closes off the leaky vessels in the majority of patients. And while these vessels reopen and leak in some patients, the treatment can be repeated, if needed, without harm to the eye.
Some seminar participants said the best hope for conquering blinding eye diseases was unraveling the sometimes complex genetics underlying many if not all of these conditions. Just last month, for example, a team of scientists announced the discovery of the first genetic link to age-related macular degeneration, which strikes 25 percent of Americans over the age of 65 and is the major cause of vision loss in the elderly. The researchers hope that by studying mutations in this gene they will gain an understanding of how the disease damages the eye, a means of identifying those at risk and methods of prevention and treatment.
Glaucoma, for example, usually involves elevated pressure inside the eye, leading eventually to the death of ganglion cells, the nerve cells that transmit information from the eye to the brain. This disease afflicts perhaps eight million Americans and causes blindness in 5,500 each year. Currently the only available treatment involves continual use of eye drops that reduce intraocular pressure. This only works if treatment is begun early.
Dr. Robert W. Nickells, an eye researcher at the University of Wisconsin in Madison, said, however, that ''new advances suggest that glaucoma could be treated during the second or even the third stage of the disease.'' The second stage involves the release of high concentrations of ''excitotoxins,'' amino acids that are toxic to nerve cells. Dr. Nickells said that several compounds that intervene in the formation of excitotoxins have been developed to treat other neurodegenerative disorders and may also prove useful in treating glaucoma.
As for the third stage, he and his colleagues have found in monkeys and rodents that ganglion cells succumb to a form of programmed cell death that appears to be controlled by three genes that act as a molecular switch. One of the genes, called bcl-x, prevents the fatal blow and might be harnessed therapeutically to override the cell death mechanism, Dr. Nickells said.
But discoveries about the genetics of eye disorders can sometimes raise more questions than they answer. For example, Dr. Fulton Wong of Duke University Medical Center reported that as many as 50 genes are believed to be involved in the progressive disease retinitis pigmentosa, which begins as night blindness and loss of peripheral vision and eventually destroys central vision, leaving people blind. Thus far, four genes have been identified, each with multiple mutations that may result in different aberrations of the condition. One of the genes that codes for the production of the visual pigment rhodopsin can exist in 92 different mutated forms, Dr. Wong reported.
This year alone, three genes for various forms of glaucoma have been identified. But Dr. Janey Wiggs, an ophthalmologist and geneticist at Tufts University School of Medicine in Boston, said: ''This is a very complicated disease, with maybe 20 or 30 genes involved. And finding genes is only the first step. Where and when is the gene required and how does it produce disease? Does it result in too much or not enough of a gene product or make a toxic product?''
Still, she and others expressed guarded enthusiasm for the prospects of gene therapy to treat various devastating eye diseases. ''The eye is accessible,'' she said. ''It can be given selective treatment, using the other untreated eye as a control to see how well the treatment is working.''
Dr. J. Timothy Stout, head of the division of ophthalmology at Children's Hospital in Los Angeles, said, ''The potential use of gene therapy is nearly limitless for the ophthalmologist.'' He and his colleagues are exploring in animals the potential of a so-called suicide gene to treat eye diseases that involve excessive cell division, such as intraocular proliferative disease, macular degeneration and diabetic retinopathy. Normally, most cells in an adult eye are not dividing. Using as a gene carrier a virus that infects only actively dividing cells, he introduces into the eye a gene that by itself is not toxic but that results in cell death when combined with the drug ganciclovir, which also does not harm normal cells. Thus, the treatment is specific for the proliferating cells involved in the eye disease.
AGING Americans expect more from their eyes these days than ever before. People in their 70's and 80's want to be able to drive, play cards, recognize people on the street, travel with their grandchildren, take advantage of senior discounts in the movies and read the books they missed while working full time.
But eyes have a way of aging that can render such expectations unrealistic. Far worse than the loss of visual acuity that prompts most middle-aged people to resort to magnifying lenses are sight-robbing diseases like glaucoma, cataracts, age-related macular degeneration, diabetic retinopathy and other retinal disorders that afflict tens of millions of Americans, usually after age 50.
The incidence of such potentially blinding disorders is increasing rapidly as the number of older people grows. Experts predict, for example, that by the year 2030, 6.3 million older Americans will develop macular degeneration, up from 1.7 million in 1995. It is a still-irreversible disorder that robs people of the central vision needed to drive, read, watch television, recognize faces, play cards or do any fine work. If Grandma Moses had had macular degeneration, her artistic talents would never have been noticed.
Fortunately, research is progressing on a number of promising new treatments, including low doses of radiation, and a combination of lasers and light-activated chemicals, both of which are used for some particularly hard-to-treat forms of macular degeneration. Other research is concentrating on how to stop toxins that damage the eye in glaucoma, and the genetics of several different eye diseases.
''Older Americans today expect to enjoy their retirement with the same visual capacity that they had in their younger years,'' said Dr. Harold Spalter, professor of ophthalmology at Columbia-Presbyterian Medical Center in New York. But, alas, as was apparent at a four-day seminar that Dr. Spalter chaired here last month, researchers are still a long way from knowing how to reverse most blinding eye disorders.
Still, major progress in understanding and treating these conditions -- and perhaps detecting them early enough to blunt their effects -- was evident at the seminar, organized by Research to Prevent Blindness, a New York-based voluntary organization. Unfortunately, though, many elderly Americans cannot afford the early detection procedures described at the seminar because Medicare and many other insurance programs do not cover such preventive measures.
For example, while insurance companies would routinely cover a visual field examination for a patient who already has glaucoma, most would not pay for this test for a person who has not yet experienced vision loss, when the disease process might be stopped without lasting vision damage.
Furthermore, an ongoing study of 2,520 men and women aged 65 to 84 in Salisbury, Md., has revealed that the usual eye chart test for visual acuity is inadequate to assess vision losses that interfere with the ability of elderly people to get around on their own, perform tasks of daily living and avoid accidents that can result in serious or fatal injuries. Rather, Dr. Sheila West, professor of ophthalmology at Johns Hopkins Medical Institutions, reported that tests for contrast sensitivity -- the ability to distinguish, say, a step from the one below it -- are more revealing of functional disability in older people.
''We have found that loss of contrast sensitivity is as important as arthritis and heart failure in determining loss of mobility in the aged,'' Dr. West said. She traced this loss to ''nonspecific retinal changes'' and the beginnings of cataracts, a gradual clouding of the lens of the eye that eventually obscures vision. However, early-stage cataracts are rarely recognized by those who have them and are often dismissed as inconsequential by eye doctors.
Sunlight, Dr. West said, is a major factor in the formation of cataracts, and the damage is cumulative. By assessing the exposure of study participants to sunlight, Dr. West and colleagues determined that for every 1 percent increase in exposure to ultraviolet-B light, the risk of developing cataracts rose by 10 percent.
''There is no threshold for sun-related damage, the dosage is cumulative and no group is immune to it,'' Dr. West said the study showed. She recommended that when out of doors, everyone -- starting in childhood -- should wear lenses that block ultraviolet light and a cap with a brim that shades the eyes.
Dr. M. Cristina Leske, head of preventive medicine at University Medical Center in Stony Brook, N.Y., and associates, identified other risk factors for cataracts. Through a five-year study of 764 patients, they found that Caucasians are three times as likely as blacks to develop cataracts. Those who take the gout medicine allopurinol face more than a two-fold increase in risk, and smokers have a 60 percent increase.
On the other hand, certain nutrients appear protective. The risk was 30 percent lower among those who took multivitamin-mineral supplements and nearly 60 percent lower among those who took a vitamin E supplement, a finding that is now being tested in a clinical trial sponsored by the National Eye Institute. Still another study of 247 women aged 56 to 71 conducted at Tufts University in Boston found that taking vitamin C supplements for more than 10 years reduced the risk of early cataracts by 77 percent and the risk of moderately advanced cataracts by 83 percent.
But while cataracts can usually be treated very successfully by surgically removing the damaged lens and replacing it with a synthetic lens implant, age-related macular degeneration, the leading cause of legal blindness in the elderly, has yet to yield to an effective treatment. Macular degeneration involves progressive damage to the cells in the center of the retina that are responsible for straight-ahead vision.
Early cases are often treated with lasers, which have the unfortunate side effect of destroying normal retinal cells as well as the damaged areas beneath them. Furthermore, after laser treatment, the vision-damaging tissue often grows back.
Dr. Dennis M. Marcus, an ophthalmologist at the Medical College of Georgia in Augusta, said that laser therapy usually cannot be used for the most severe form of the disease -- so-called wet macular degeneration, which involves the growth of leaky blood vessels beneath the central retina. Instead, he and his colleagues are testing low-dose radiation to destroy the blood vessels but spare the normal retinal cells. Thus far, 100 patients have been treated in a clinical trial that will eventually involve 500 people with wet macular degeneration. While it is too soon to evaluate the effectiveness of the treatment, Dr. Marcus said that he has seen no radiation-induced complications.
Another clinical study is testing a technique called photodynamic therapy. It starts with the intravenous administration of a photosensitive dye that collects in the damaging blood vessels that are growing beneath the retina. The eye is then exposed to laser light that activates the dye, destroying those vessels only. Dr. Joan W. Miller, an ophthalmologist at the Massachusetts Eye and Ear Infirmary, said that preliminary studies showed that the technique effectively closes off the leaky vessels in the majority of patients. And while these vessels reopen and leak in some patients, the treatment can be repeated, if needed, without harm to the eye.
Some seminar participants said the best hope for conquering blinding eye diseases was unraveling the sometimes complex genetics underlying many if not all of these conditions. Just last month, for example, a team of scientists announced the discovery of the first genetic link to age-related macular degeneration, which strikes 25 percent of Americans over the age of 65 and is the major cause of vision loss in the elderly. The researchers hope that by studying mutations in this gene they will gain an understanding of how the disease damages the eye, a means of identifying those at risk and methods of prevention and treatment.
Glaucoma, for example, usually involves elevated pressure inside the eye, leading eventually to the death of ganglion cells, the nerve cells that transmit information from the eye to the brain. This disease afflicts perhaps eight million Americans and causes blindness in 5,500 each year. Currently the only available treatment involves continual use of eye drops that reduce intraocular pressure. This only works if treatment is begun early.
Dr. Robert W. Nickells, an eye researcher at the University of Wisconsin in Madison, said, however, that ''new advances suggest that glaucoma could be treated during the second or even the third stage of the disease.'' The second stage involves the release of high concentrations of ''excitotoxins,'' amino acids that are toxic to nerve cells. Dr. Nickells said that several compounds that intervene in the formation of excitotoxins have been developed to treat other neurodegenerative disorders and may also prove useful in treating glaucoma.
As for the third stage, he and his colleagues have found in monkeys and rodents that ganglion cells succumb to a form of programmed cell death that appears to be controlled by three genes that act as a molecular switch. One of the genes, called bcl-x, prevents the fatal blow and might be harnessed therapeutically to override the cell death mechanism, Dr. Nickells said.
But discoveries about the genetics of eye disorders can sometimes raise more questions than they answer. For example, Dr. Fulton Wong of Duke University Medical Center reported that as many as 50 genes are believed to be involved in the progressive disease retinitis pigmentosa, which begins as night blindness and loss of peripheral vision and eventually destroys central vision, leaving people blind. Thus far, four genes have been identified, each with multiple mutations that may result in different aberrations of the condition. One of the genes that codes for the production of the visual pigment rhodopsin can exist in 92 different mutated forms, Dr. Wong reported.
This year alone, three genes for various forms of glaucoma have been identified. But Dr. Janey Wiggs, an ophthalmologist and geneticist at Tufts University School of Medicine in Boston, said: ''This is a very complicated disease, with maybe 20 or 30 genes involved. And finding genes is only the first step. Where and when is the gene required and how does it produce disease? Does it result in too much or not enough of a gene product or make a toxic product?''
Still, she and others expressed guarded enthusiasm for the prospects of gene therapy to treat various devastating eye diseases. ''The eye is accessible,'' she said. ''It can be given selective treatment, using the other untreated eye as a control to see how well the treatment is working.''
Dr. J. Timothy Stout, head of the division of ophthalmology at Children's Hospital in Los Angeles, said, ''The potential use of gene therapy is nearly limitless for the ophthalmologist.'' He and his colleagues are exploring in animals the potential of a so-called suicide gene to treat eye diseases that involve excessive cell division, such as intraocular proliferative disease, macular degeneration and diabetic retinopathy. Normally, most cells in an adult eye are not dividing. Using as a gene carrier a virus that infects only actively dividing cells, he introduces into the eye a gene that by itself is not toxic but that results in cell death when combined with the drug ganciclovir, which also does not harm normal cells. Thus, the treatment is specific for the proliferating cells involved in the eye disease.
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