As per your context, this is it, methinks.

Cheers,

Karina ;)

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Note added at 8 mins (2008-04-15 23:36:30 GMT)
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African Americans May Have Less Risk for
Developing Macular Degeneration

BALTIMORE, February 2008 — African Americans may have less risk of developing advanced macular degeneration (AMD) than Caucasians, according to recent findings by Johns Hopkins School of Medicine scientists.

Early signs of AMD include formation of yellowish spots (drusen) in the inner back of the eye (retina), where vision processing occurs. In a study involving 2,520 participants of average ages of 73.5 years, researchers found that larger drusen and those closer to the eye's center were more likely to occur in Caucasians than in African Americans.

Study authors concluded that more Caucasians than African Americans were likely to develop advanced and potentially blinding forms of macular degeneration. Researchers said more research is needed to determine why African Americans are less likely to have significant degenerative changes associated with AMD, such as those that occur in central portions of the retina.