Macular Degeneration

The following study indicates that there is a strong association between macular degeneration and smoking. To me this suggests that cadmium toxicity should be a primary suspect in the etiology of macular degeneration. Hong Kong Med J 2000 Jun;6(2):195-202: The association between cigarette smoking and ocular diseases.

Cheng AC, Pang CP, Leung AT, Chua JK, Fan DS, Lam DS

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin.

OBJECTIVE: To review the effect of smoking on common ocular disorders. DATA SOURCES: Medline literature search, 1966 to 1999. STUDY SELECTION: The following key words were used: smoking; Graves' disease, age-related macular degeneration; glaucoma; cataract. DATA EXTRACTION: Epidemiological and experimental studies were reviewed. DATA SYNTHESIS: Cigarette smoking is an important risk factor for cardiovascular, respiratory, and malignant diseases. There is also a strong association between smoking and a number of common eye diseases, which include Graves' ophthalmopathy, age-related macular degeneration, glaucoma, and cataract. Despite the multifactorial aetiology of these ocular syndromes, smoking is an independent risk factor that has dose-response effects. It causes morphological and functional changes to the lens and retina due to its atherosclerotic and thrombotic effects on the ocular capillaries. Smoking also enhances the generation of free radicals and decreases the levels of antioxidants in the blood circulation, aqueous humour, and ocular tissue. Thus, the eyes are more at risk of having free-radical and oxidation attacks in smokers. CONCLUSION: Smoking, if continued, may perpetuate further ocular damage and lead to permanent blindness. Cessation of smoking and avoidance of passive smoking is advised to minimise the harmful effects of smoking on the eyes.

Ginkgo biloba may have promise in the treatment of macular degeneration.

Arch Phys Med Rehabil 2000 May;81(5):668-78: Ginkgo biloba extract: mechanisms and clinical indications.

Diamond BJ, Shiflett SC, Feiwel N, Matheis RJ, Noskin O, Richards JA, Schoenberger NE

Department of Research, Center for Research in Complementary and Alternative Medicine, Kessler Medical Rehabilitation Research and Education Corporation, West Orange, NJ 07052, USA.

OBJECTIVE: Ginkgo biloba may have a role in treating impairments in memory, cognitive speed, activities of daily living (ADL), edema, inflammation, and free-radical toxicity associated with traumatic brain injury (TBI), Alzheimer's dementia, stroke, vasoocclusive disorders, and aging. The purpose of this review is to provide a synthesis of the mechanisms of action, clinical indications, and safety of Ginkgo biloba extract. DATA SOURCES: Empirical studies, reviews, chapters, and conference proceedings were identified in the following databases: Medline, the Research Council for Complementary Medicine based on the British Library database, and Psychlnfo. Ginkgo biloba, EGb 761, Tanakan, Tebonin, Rokan, and LI 1370 were the principal index terms. STUDY SELECTION AND DATA EXTRACTION: Controlled clinical studies with both positive and negative findings are included, in addition to animals studies illustrating mechanisms of activity. DATA SYNTHESIS: Ginkgo has shown activity centrally and peripherally, affecting electrochemical, physiologic, neurologic, and vascular systems in animals and humans with few adverse side effects or drug interactions. Ginkgo shows promise in patients with dementia, normal aging, and cerebrovascular-related disorders. Clinical indications include memory, information processing, and ADL. CONCLUSIONS: Ginkgo shows promise in treating some of the neurologic sequelae associated with Alzheimer's disease, TBI, stroke, normal aging, edema, tinnitus, and macular degeneration. Mechanisms of action may include antioxidant, neurotransmitter/receptor modulatory, and antiplatelet activating factor properties. While safe, caution is advised when recommending ginkgo to patients taking anticoagulants. Future studies should examine dose effects, component activity, mechanisms, and clinical applications.

J Med Genet 2000 Feb;37(2):83-7

Genetic susceptibility to age related macular degeneration.

Yates JR, Moore AT

Department of Medical Genetics, University of Cambridge, Box 134, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.

Age related macular degeneration (AMD) is the leading cause of visual impairment in the elderly and a major cause of blindness in the developed world. The disease can take two forms, geographic atrophy and choroidal neovascularisation. The pathogenesis of AMD is poorly understood. There are undoubtedly environmental and other risk factors involved and the adverse effect of smoking is well established. Several studies have shown that genetic factors are important but leave uncertainty about the magnitude and nature of the genetic component and whether it varies with the type of AMD. Several hereditary retinal dystrophies show similarities to AMD and these genes are potential candidate susceptibility genes. Particular interest has focused on the ABCR gene which is responsible for autosomal recessive Stargardt macular dystrophy. It has been claimed that heterozygotes for ABCR mutations are predisposed to AMD but the data are conflicting. Studies of the genes responsible for autosomal dominant Sorsby fundus dystrophy, Doyne honeycomb retinal dystrophy, and Best disease have given negative results. In one large AMD family, linkage has been reported to markers in 1q25-q31. Recent data suggest that the ApoE epsilon4 allele may be associated with reduced risk of AMD. A better understanding of the genetic factors in AMD would contribute to understanding the pathogenesis. If those at risk could be identified it may be possible to modify lifestyle or develop novel therapies in the presymptomatic stage to prevent disease or decrease its severity.

Publication Types:

Ophthalmologica 1992;205(2):100-4

[Changes in Contrast Sensitivity after Iodine Treatment in Bad Hall in Patients with Age-Related Maculopathy].

[Article in German]

Rieger G

Augenabteilung des Paracelsus- Institutes des Landes, Oberosterreich in Bad Hall.

After a cure with iodine in Bad Hall (Upper Austria), patients with age-related maculopathy repeatedly reported improvement in visual power: the picture seen seems to be clearer on the whole or more distinct. These statements were checked in 50 patients with beginning age-related macula degeneration ('dry form') using the 'Vision Contrast test system (VCTS 6500)'. The analysis of the results showed that there is indeed a statistically highly significant improvement in contrast sensitivity after the cure (p < 0.0001). The spontaneous observations of the patients were therefore confirmed by the study.

PMID: 1475080, UI: 93116974

J Ophthalmic Nurs Technol 1996 Sep-Oct;15(5):186-9

Indocyanine green dye for choroidal angiography.

Burke M

Wills Eye Hospital, Diagnostic Photography Department, Philadelphia, Pennsylvania, USA.

1. Patients must be assessed for iodine allergy prior to indocyanine green administration. A scrupulous injection technique will ensure a safe diagnostic procedure. 2. Indocyanine green dye is used for choroidal angiography to diagnose age-related macular degeneration. 3. Indocyanine green dye has no discernable after effects for the patient. It is nontoxic and wholly removed by the liver. Indocyanine green does not show up as skin discoloration.

PMID: 9120865, UI: 97250060

Viagra Seen As Potential Treatment For Vision Problems

June 5, 2000

SAN ANTONIO (San Antonio Express-News) - Viagra has become firmly imbedded in the American vocabulary since the drug debuted two years ago as a treatment for men with sexual dysfunction.

But debate continues among doctors and researchers, who have cautioned that not much is known about its effect on other systems in the body. Eye specialists, in particular, have warned high doses of Viagra can affect the delicate chemistry of the eye in some patients and cause temporary visual problems.

Now, researchers from the University of Texas Health Science Center say their work suggests Viagra, or sildenafil, should be studied as a potential treatment for patients with macular degeneration, the leading cause of blindness in older individuals.

Other experts warned it is far too soon to make even that qualified suggestion.

"We have a long way to go, but so far we have nothing but good cause for guarded optimism," said Dr. William Sponsel, an associate professor of ophthalmology and lead author of the study.

Health science center researchers found a low dose of sildenafil improved the blood flow to the eye and increased contrast sensitivity in 12 middle-aged adults who had no eye disease.

Diminished blood flow is a culprit in macular degeneration, an untreatable condition that is slowly deteriorating vision in some 13 million Americans, most of them over age 55.

Macular degeneration causes blurry or fuzzy vision, distortions and dark spots in the center of the field of vision.

"We're most excited here about the prospects for the biggest class of disorders that we currently can't treat," Sponsel said.

Results of the study, which was not funded by Viagra manufacturer Pfizer Inc., were published last Wednesday in the correspondence section of the New England Journal of Medicine, in which doctors exchange brief reports on topics of interests.

Other ophthalmologists, however, expressed reservations about the findings, noting that the San Antonio study was small and involved healthy patients who were younger than those typically afflicted with macular degeneration.

The study also did not have a control, or a comparison group that did not take the drug, noted Dr. Michael Marmor, a professor of ophthalmology at the Stanford University School of Medicine in California.

"This is a preliminary study ... using a low dose, without any controls, that really makes it difficult to draw any firm conclusions," Marmor said, adding: "I think it is premature" to conclude that Viagra could help older patients with deteriorating eyesight."

Two years ago, Marmor published research indicating high doses of Viagra temporarily increased light sensitivity and altered color perception in some patients.

He said patients who take the drug should be made aware of this and understand that doctors do not know much about the long-term effects.

Dr. Juan E. Grunwald, a professor of ophthalmology at the University of Pennsylvania, said the study builds on a finding that blood flow is diminished to the choroid, a tissue that nourishes the retina.

Following is a study mentioning that lutein may help macular degeneration.: Macular Pigment and Risk for Age-Related Macular Degeneration in Subjects from a Northern European Population.

Beatty S, Murray IJ, Henson DB, Carden D, Koh HH, Boulton ME

University Department of Ophthalmology, Manchester Royal Eye Hospital, Manchester. Visual Sciences Laboratory, Department of Optometry and Neuroscience, University of Manchester Institute of Science and Technology, Manchester. Department of Optometry and Vision Sciences, Cardiff University, United Kingdom.

[Record supplied by publisher]

PURPOSE. Age and advanced disease in the fellow eye are the two most important risk factors for age-related macular degeneration (AMD). In this study, the authors investigated the relationship between these variables and the optical density of macular pigment (MP) in a group of subjects from a northern European population. METHODS. The optical density of MP was measured psychophysically in 46 subjects ranging in age from 21 to 81 years with healthy maculae and in 9 healthy eyes known to be at high-risk of AMD because of advanced disease in the fellow eye. Each eye in the latter group was matched with a control eye on the basis of variables believed to be associated with the optical density of MP (iris color, gender, smoking habits, age, and lens density). RESULTS. There was an age-related decline in the optical density of macular pigment among volunteers with no ocular disease (right eye: r(2) = 0.29, P: = 0.0006; left eye: r(2) = 0.29, P: < 0.0001). Healthy eyes predisposed to AMD had significantly less MP than healthy eyes at no such risk (Wilcoxon's signed rank test: P: = 0.015). CONCLUSIONS. The two most important risk factors for AMD are associated with a relative absence of MP. These findings are consistent with the hypothesis that supplemental lutein and zeaxanthin may delay, avert, or modify the course of this disease.