Eye Didn't Know!

Macular Degeneration and Cataract Surgery

Did you know? For many years it has been controversial whether having cataract surgery could accelerate the development of advanced macular degeneration. Some patients have cataract surgery, and not long after, develop worsening of their macular degeneration. Patients, of course, will often blame the cataract surgery. (I have at least one patient who falls into that category). What confounds this logic, though, is that cataracts occur with aging, as does macular degeneration. Patients may experience macular degeneration worsening with or without having had cataract surgery.

At last a well-designed study has addressed this question. The Age-Related Eye Disease Study (AREDS) was conducted between 1992 and 2005 and followed over 8,000 eyes of over 4,000 patients. The study was designed to assess the effect of antioxidants and mineral supplements on macular degeneration. The study assessed the development of advanced macular degeneration and history of cataract surgery at six month intervals during the study.

The results showed that appromately 20% of the eyes underwent cataract surgery during the study. Of the eyes undergoing surgery, 6% developed severe macular degeneration. Of the eyes not undergoing surgery, 7% developed severe macular degeneration. The results of the two groups did not significantly differ statistically.

It can be safely said that modern cataract surgery in unlikely to be related to worsening of macular degeneration.

Did you also know? The AREDS study originally found that their combination of zinc and antioxidants (now found in Ocuvite and others) modestly reduced the risk of progression for eyes with early signs of macular degeneration. The AREDS II study, ongoing now, is investigating the possible roles of omega-3 fatty acids, lutein, and zeaxanthin. It is also investigating if the dosage of zinc can be reduced and whether beta-carotene can be eliminated (for safety reasons in some patients).

More fishy news

Did you know? A study published in the August 2008 issue of the American Journal of Clinical Nutrition showed that eating oily fish (like salmon) more than once a week may lower the odds of developing severe macular degeneration by 50%, compared to those who eat oily fish less than once per week. The same study showed that those who consumed the most fish reduced their odds by 2/3. This study did not address the use of fish-oil supplements, so do yourself a favor and enjoy the real fish!

Did you also know? These results are similar to a study I mentioned last year, published in the Archives of Ophthalmology.

(photo: wikimedia commons)

New approach to macular degeneration treatment

Did you know? Researchers at the University of Florida are testing a new compound, Compstatin, for its effectiveness in preventing complications of macular degeneration. This small protein blocks complement, which promotes inflammation in the body. It is believed that complement is involved upstream in the process which eventually leads to abnormal blood vessels forming and bleeding in macular degeneration.

Three volunteers with macular degeneration have had their eyes injected with compstatin, and they are now being monitored for side-effects. I am very interested to know the frequency that these medicines would be needed, as it is not pleasant to have medicine injected into the eye!

Did you also know? The drugs Avastin and Lucentis, both produced by Genentech, have revolutionized treatment of macular degeneration. These compounds, unlike any previous treatment, can cause regression of bleeding in the eye and improvement of vision!

Antioxidants and early Macular Degeneration

Did you know? The makers of antioxidants, including the ones used in the AREDS study, often make vague claims that these vitamins "promote eye health" and thus imply that they are needed by the general population. Yet there is NO evidence that this is so. A new report in the British Medical Journal analyzed the results of nine prospective studies involving nearly 150,000 subjects. They found no evidence that antioxidant supplement therapy decreased the incidence of early macular degeneration. Different studies looked at different substances, but included the following: vitamin A, vitamin C, vitamin E, zinc, lutein, zeaxanthin, alpha-carotene, beta-carotene, beta-cryptoxanthin and lycopene.

Did you also know? The original AREDS study (Age Related Eye Disease Study) showed that a combination of antioxidants and zinc reduced the progression of moderate macular degeneration to advanced vision loss. This is a specific indication for which ophthalmologists prescribe these supplements. This does not equal "promoting eye health" by encouraging the general population to use these supplements.

Smoke Your Way to Vision Loss

Did you know? A ten year study of 3,654 Australians has shown that current smokers have four times the risk of advanced macular degeneration compared to non-smokers! Smokers who had low levels of HDL (good cholesterol) or low fish intake had an even higher risk. Read more here.

(image courtesy wikipedia commons)

Did you also know? Many doctors prescribe vitamins to prevent macular degeneration, but fail to inquire about smoking habits. The risk of vision loss from smoking is an order of magnitude higher than the risk from a diet low in antioxidants, zinc, lutein and zeaxanthin.

More Macular Degeneration-Nutrition News

Did you know? There's clearly more to the macular degeneration/nutrition link than what is on the radar screen of most ophthalmologists. A new study showed that vitamins B6, B12, and folate may be protective. A group of over 5000 women at risk for heart disease was randomized to placebo or Vitamin B6, B12 and folate. After seven years, the group taking the vitamins had 41% less visually significant macular degeneration.

Did you also know? The study was designed to assess whether these vitamins would lower heart disease (by lowering homocysteine levels). There was NO difference in heart disease in the two groups!

Fishy news

Did you know that eating fish may help prevent macular degeneration? Two studies in this month’s Archives of Ophthalmology showed that advanced macular degeneration occured less often in those who ate fish regularly compared to those that ate fish rarely. One study examined the eyes and took a dietary survey of over seven thousand subjects. Those who ate fish at least weekly had less than half the prevalence of advanced macular degeneration compared to those who ate fish less than twice a month. Another study showed a 35% decrease in advanced macular degeneration for those who ate more broiled or baked fish (but not fried!). The authors postulate that fish oils may decrease inflammation and decrease the formation of abnormal new blood vessels, both of which occur in advanced macular degeneration. Whether or not fish-oil supplements are helpful in macular degeneration is not known.

(image courtesy wikipedia commons)

Did you also know? The first of these studies also found that drinking milk was related to less early macular degeneration. (Possibly related to its vitamin D content.)

(image courtesy wikipedia commons)

New use for old Chinese remedy?

Did you know? A synthetic version of bear bile, used in Chinese medicine for millenia, is being tested for its ability to prevent cell death which occurs in macular degeneration, glaucoma, and retinitis pigmentosa. TUDCA and UDCA are components of bile, which help us digest fats. Humans have small amounts of these compounds, but bear bile has large amounts. Synthetic versions are available and inexpensive. Researchers at Emory University tested these compounds. When injected into mice, they preserved the function and structure of retinal cells in two different mouse models of human retinal degeneration. Read about it here.

Did you also know? The researchers stress that the compounds they are testing are synthetic, and do not involve harvesting bear bile! In fact, UDCA, or ursodiol, is available orally as a treatment for liver disease.

Beta Carotene and Macular Degeneration

Did you know? A new study has been released in Archives of Ophthalmology, which followed over 22,000 male physicians for twelve years. Half were randomized to take beta-carotene supplementation, half took a placebo. There was NO statistical difference in the incidence of macular degeneration between the two groups. Supplementation had neither a beneficial or harmful effect. This study is notable in its rigorous design, number of subjects, and length of follow-up. The authors are among the most respected in the field of ocular epidemiology.

Did you also know? The well-known AREDS study looked at supplementation with high doses of zinc, beta-carotene, and vitamins C and E. This study showed a modest benefit for those with a high-risk of macular degeneration, (those with significant drusen in their maculas), but no measurable effect for those with no risk factors, since the risk for these patients was low to begin with.

Macular Degeneration Eyedrops?

Did you know? A Virginia company, Ocucure Therapeutics, is attempting to develop an eyedrop which could inhibit or reverse the damage caused by macular degeneration. In the wet form of macular degeneration, abnormal blood vessels form in the back of the eye, leading to bleeding, scarring, and vision loss. A complicated molecular cascade triggers this process. Ocucure has developed a treatment based on inhibiting tubulin, which is a cellular component involved in blood vessel formation. The company claims that this treatment works in animal models, and penetrates into the eye in an eyedrop form. Human trials await.

Did you also know? If this therapy should prove to work for macular degeneration, then it would also have a potential use in diabetic retinopathy, also caused by abnormal blood vessel formation.