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).

Critical Thinking

Brian Dunning is the host of one of my favorite podcasts, called Skeptoid.

Since not everyone listens to podcasts, Brian produced a video which encapsulates what you need to know to think critically. This ability is crucial to evaluating medical and nutritional claims, as well as claims you hear everyday in the media or on the internet.

My blog frequently features possible new treatments for eye diseases. These claims must be evaluated critically. Brian's video is a good place to begin. Especially valuable is his concise description of how a proper clinical trial is designed and implemented.

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)

Alternative Therapies for Glaucoma?

Did you know? It is said that 50% of patients with glaucoma use "alternative" therapies, that is, therapies other than those prescribed by their physician. The rate may be higher in Asian populations. The question is, do they work??? A prominent glaucoma specialist from San Francisco, John Hetherington, M.D., recently reviewed the literature on the subject. He reached the following conclusions:

Vitamins A, B1, B12, C, and E, as well as antioxidant supplements, had no meaningful effect on intraocular pressure or glaucoma progression.

Marijuana decreases eye pressure, but its effects are very short–lived with significant side–effects. Topical application of its components (there are over 400!) has not yet shown to be effective, but is being studied.

Ginkgo biloba increases ocular blood flow and thus may protect the optic nerve. Dr. Robert Ritch is a specialist who has advocated gingko use for glaucoma for many years. Gingko may cause side effects such as bleeding, especially when used with aspirin, so should be used with caution or after consultation with a primary care physician.

There is no evidence that bilberry is beneficial for glaucoma or optic nerve health.

Drinking excess water can raise eye pressure temporarily.

Alcohol can decrease eye pressure temporarily, but obvious toxicity can result with excess!

Meditation produces insignificant reduction in eye pressure.

Acupuncture has not be shown to affect eye pressure.

Exercise has a significant eye pressure lowering effect over time.

In summary, exercise and possibly gingko are the only alternative therapies which currently may be effective in glaucoma. So save your money and keep walking!

Did you also know? Yoga exercises which feature inversion for long periods of time should definitely be avoided in glaucoma, as they can increase eye pressure greatly!

(photo by Joseph Renger, wikimedia commons)

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.

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.

Cataract Cure???

Did you know? A company in Philadelphia, Othera Pharmaceuticals, is testing an eyedrop which they hope will retard the progression of cataracts. A cataract occurs when the natural lens within the eye becomes cloudy. It is thought that one stimulus for cataract progression is oxidation. Othera is testing a compound, OT-551, which is a potent anti-oxidant, and is able to penetrate into the eye. They are testing the compound first in patients who have undergone a vitrectomy (a surgery for retinal problems) because these patients frequently develop cataracts over a short period.

Did you also know? The concentration of Vitamin C in the front of the eye is many times greater than its concentration in the rest of the body. This may help prevent cataracts.