October 2010

 

OPHTHALMOLOGY NEWS

 

Staving off cataracts with caffeine


by Maxine Lipner Senior EyeWorld Contributing Editor

   

Investigating caffeine's ocular potential

The benefits of caffeine may exceed simply giving patients a jolt in the morning. New research suggests that caffeine may help to keep cataracts at bay, according to Shambhu D. Varma, Ph.D., professor of ophthalmology and biochemistry, University of Maryland School of Medicine, Baltimore. In the March issue of Molecular Vision, investigators led by Dr. Varma found that cataracts were prevented in rat eyes in which caffeine was administered.

Dr. Varma views stemming the cataract tide as an important goal. "Cataract is one of the leading causes of blindness all over the world," he said. "About 50% or more of blindness is due to this disease, and so far no medical treatment is available."

The bioflavonoid connection

Dr. Varma has been striving for some time to find a compound that can effectively prevent this condition. An earlier study of bioflavonoid showed promise. "In my earlier study we found that cataracts can be prevented by bioflavonoid," Dr. Varma said. "That was the first demonstration of the fact that cataract is a preventable disease." Such bioflavonoids are derived from plants. These can stave off cataracts in two ways. "They inhibit oxidative stress, which is caused by oxygen radicals in the eye," Dr. Varma said. The bioflavonoids take away the oxygen radicals that can otherwise lead to cataract damage.

Secondly, they can stop cataract formation directly by inhibiting the aldose reductase enzyme. "The activation of aldose reductase causes oxidative stress," Dr. Varma said. "The bioflavonoid property of inhibiting the enzyme as well as scavenging oxygen radicals is a powerful anti-cataractic agent."

Dr. Varma hypothesized that many plant products that are rich in bioflavonoids should be able to prevent cataract formation. With this in mind, he considered the use of tea. "We found that if we give tea extracts to experimental animals, the cataract degeneration is profoundly protected," Dr. Varma said. As he became more interested it occurred to Dr. Varma that unfortunately, the way most tea is consumed might make this clinically impractical. "I figured this would probably not work in actual practice because when tea or coffee is made for manufacturing purposes it is sterilized and has to go through some curing process," Dr. Varma said. "During the curing and sterilization process many of the bioflavonoids are oxidized."

Testing caffeine

With this in mind Dr. Varma became curious about what compounds in addition to bioflavonoid might be present in relatively large quantities in tea or coffee and robust enough not to get oxidized. Caffeine seemed to be a natural choice. "Looking at the structure of caffeine I visualized that this could be a powerful antioxidant because on a molecule of caffeine there is a place I call carbon 18 and it is highly potent to take away from the reactive oxygen species and form something like a uric acid compound," Dr. Varma said. "This is a double agent because by itself caffeine will scavenge the oxygen radicals and its product is also an antioxidant." Dr. Varma first tried a test tube experiment to see if the caffeine could prevent light damage to the lens. He incubated rat lenses with ultraviolet light. "Of course it is expected that UV [ultraviolet] damages, but the addition of a little caffeine prevents it beautifully," he said. "The hypothesis was workingthe caffeine was taking away the oxygen radical that is produced by the UV and therefore it protects the lens from ongoing damage."

He then tested this in a clinical situation in which an animal was directly exposed to light under conditions known to induce oxidative stress. For this he chose a galactose compound, which is known to be a strong catarogenic agent, sodium seramide. "If we gave sodium seramide to the rat pups on day 7 or 8, by the time they opened their eyes about 1 week later they had cataracts," Dr. Varma said.

Investigators simultaneously treated a second group of rat pups with caffeine in addition to the sodium seramide. "When they opened their eyes, the rats who we gave sodium seramide only to had cloudy lenses," he said. "In the caffeine group the cataracts were largely prevented."

In the most recent study, investigators induced oxidative stress by administering a 24% galactose diet to young adult rats in one group and the same diet plus 1% caffeine to rats in another group. They once again found that in the caffeine group the cataract was prevented. In addition, they measured biochemical parameters to determine whether oxidative stress was indeed inhibited. "We found that the biochemical damage to the lens is also prevented simultaneously," Dr. Varma said. From a dietary perspective it may not be practical to consume caffeine in the order of 500 milligrams every day, so Dr. Varma has been working on incorporating caffeine into eye drops that could be administered by patients. Exper-iments with the drops in rats have been very encouraging. Overall, Dr. Varma is enthusiastic about the potential of caffeine for cataract prevention and more. He thinks that caffeine may have a range of ophthalmic possibilities. "At the present time I am certain that caffeine is a good compound to get into the eye," he said. "I hypothesize that similar to the lens, it might be good in the retina, too."

Editors' note: Dr. Varma has no financial interests related to his comments.

Contact information

Varma: savarm001@umaryland.edu

Staving off cataracts with caffeine Staving off cataracts with caffeine
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