Micronutrients in other macular diseases

I have received questions that ask whether the vitamins and lifestyle recommendations for AMD apply to other diseases such as Best Disease and Myopic degeneration.

Best Disease is a macular dystrophy that usually affects young or middle-aged patients and is characterized by a yellow vitelliform (egg-like) lesion in the macula. Best disease is caused by a mutation in bestrophin, a protein necessary for transport of chloride in the retinal pigment epithelium. The retinal pigment epithelium, or RPE, is the layer of cells immediately beneath the photoreceptors and is vital for visual function.

I asked my colleague, Dr. Edwin Stone, the world’s expert on Best Disease, whether there was any plausible reason to recommend vitamins for these patients. He said that there was no reason to believe that they would help and that he didn’t recommend any nutritional supplements for patients with this disease. He pointed out that nutritional supplements can be harmful such as the increased rate of lung cancer in smokers who took beta-carotene.

Dr. Stone believes however, that eyes with Best disease are prone to bleed beneath the retina after trauma. He therefore recommends that patients with this disease protect their eyes with goggles when engaging in sports where the eye could be struck with a ball or inadvertently by an opponent.

Myopic degeneration is caused by a large eyeball which causes a stretching and thinning of the retina, choroid, and sclera. It usually starts in middle-age with round areas of RPE atrophy and lacquer cracks in Bruch’s membrane beneath the RPE. The degeneration is roughly associated with the degree of myopia however some patients with very high myopia get minimal degeneration whereas others with less myopia have severe changes. It seems reasonable to me that AREDS-type vitamins may reduce the stress to the outer retina and retard the progression of myopic degeneration. There are no studies that have tested nutritional supplements in myopic degeneration however, and many of my colleagues disagree with me. I recommend to my patients who have myopic degeneration to at least take a multivitamin a day or perhaps half of the AREDS dose. This recommendation “splits the difference,” so to speak, yielding a possible benefit while reducing the risk of unknown side-effects from the full AREDS dose over many years.

References:

1. Stone E, Nichols, B, Streb L, Kimura A, Sheffield V, “Genetic Linkage of vitelliform macular degeneration (Best Disease) to chromosome 11q13” Nat Genet. 1992;42:156-159,

2. Petrukhin K, Koisti, M, Bakall B, et al. “Identification of the gene responsible for Best Macular Dystrophy” Nat Genet. 1998;19:241-247