September 27, 2002.
Evidence has been growing in recent years that a tiny part of the eye's retina, termed the macular pigment, may give the eye in-built protection from age-related macular degeneration (AMD).
Research findings strongly indicate that people are at greater risk of developing AMD if the density of their macular pigment is low. The macular pigment is entirely made up of lutein and zeaxanthin, plant pigments found in many fruits and vegetables. It may be possible to increase macular pigment density and thereby reduce the risk of the disease developing by simply adding extra lutein and zeaxanthin to the diets of those at risk; however, this work is not yet complete and the case has yet to be proved.
New research by Dr. Ian Murray and his group, from the department of optometry and neurosciences at the University of Manchester, has provided further evidence in support of this theory. It has also raised the possibility that patients already experiencing early stages of AMD may even be able to delay or prevent its progress through similar dietary intervention.
The work is supported by the U.K. Department of Health under the MedLINK programme (the LINK program for medical devices).
Murray, who presented his group's latest findings to the annual meeting of the Association for Research in Vision and Ophthalmology in Florida, said: "I have seen many patients who are suffering from the disabling effects of AMD. Of course we are excited by the prospect that a simple addition to the diet may impede the progress of the disease and prevent others who are at risk, experiencing such problems. Right now, dietary intervention is the only hope for most of them."
In one study, Murray's group selected eight patients at an early stage of development of the disease. Age 60-81, these patients so far have normal visual acuity. They were compared with "normal" subjects, matched for sex, eye-color, and age. The researchers observed, as in earlier studies, that eyes at risk of developing early-stage AMD (because of AMD symptoms in the fellow eye) have lower macular pigment density than eyes without such risk, adding credibility to the theory that the macular pigment has an AMD-protective role.
In the second ongoing study, the researchers gave a daily supplement of lutein (in the ester form) to 8 patients (6 from the first group) and to 8 normal subjects, over a period of 18 weeks, and measured the effects.
Interim data, after 12 weeks of supplementation, indicated that the density of macular pigments in both patients and normal subjects increased at the same rate. Further, the researchers found that, where patients already had AMD in one eye, both eyes responded equally well to supplementation.
The researchers' conclusion is that the disease does not stop lutein from being deposited in the retina, at least in the early stages of AMD. Based on the theory that higher macular pigment density protects against retinal damage, the corollary of this finding is that dietary intervention may be beneficial for those with early-stage AMD as well as those considered at risk of developing the disease.
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