Age-related Macular Degeneration (AMD)

AMD is not a feature of VHL. Nonetheless, the vascular irregularities in the macula are often treated with laser as in VHL, and angiogenesis inhibitors are being developed to slow the advancement of vascular damage in the retina. These same drugs are expected to be helpful with VHL. Altheada provides us with a discussion of AMD to help us understand the similarities between AMD and VHL, and suggesting some nutritional supplements that have been found to be helpful with AMD.

What is a macula? The macula is the small, yellowish central portion of the retina and it is the area providing the clearest, most distinct vision. When one looks directly at something, the light from that object forms an image on one’s macula. A healthy macula ordinarily is capable of achieving at least 20/20 (“normal”) vision, even if this is with a correction with glasses or contact lenses.

What is age-related macular degeneration? Macular degeneration is a hereditary ocular disease. Age-related macular degeneration (AMD) is not hereditary, but may sometimes be a consequence of aging, and is the leading cause of irreversible blindness among Americans 65 and older. “Dry” macular degeneration generally is caused by a thinning of the macula’s layers, and vision loss typically is gradual. However, tiny, fragile blood vessels can develop underneath the macula. “Wet” macular degeneration can result when these blood vessels hemorrhage, and blood and other fluid further can destroy macular tissue, even causing scarring. In this case, vision loss can be rapid, over months or even weeks.

Macular tissue destroyed by either dry or wet macular degeneration cannot be repaired. In the case of the wet form, a special laser can be used to seal the leaking blood vessels in the retina. However, (1) the tiny spots where the laser burns the retina will lose vision permanently, and (2) other blood vessels may leak in the future, requiring further laser treatment.

The earliest symptom of macular degeneration usually is persistently blurred vision. As more cells of the macula are destroyed, objects become distorted (for instance, straight lines become crooked). Eventually, a small blind spot in the central visual field can develop and grow in size. This can progress to the point of “doughnut” vision, where people’s faces are unrecognizable when looking directly at them, yet peripheral vision remains unaffected.

How is all of this related to VHL? There is no direct connection between VHL and AMD. Sometimes, people with VHL have macular degeneration, glaucoma and/or cataracts. In addition, treating the angiomas on the retina, resulting from VHL, can cause conditions similar to AMD. But the primary reason for this article is to help you understand why a treatment for AMD might also be effective for VHL. Angiomas are small knots of blood vessels that can, themselves, leak and damage the vision very much like some forms of macular degeneration.

Naturally occurring carotenoids in the macula, lutein and zeaxanthin (molecular cousins of beta carotene and vitamin A), have been shown to be effective protectants against degeneration of the macula. These pigments absorb and filter out near-to-blue ultraviolet radiation, acting essentially as built-in macular “sunglasses” -- which potentially is the most damaging electromagnetic radiation reaching the macula. The greater the amount of macular pigment, the less the risk of macular degeneration. Lutein and zeaxanthin are found particularly in yellow fruits and in green leafy vegetables (especially vegetables such as spinach, kale, collard greens, and broccoli), and in eggs, and as nutritional supplements. A half cup a day of one of these vegetables (cooked) will provide the recommended daily amount.

Getting these vitamins from food rather than pills provides other phytochemicals that might act in a synergistic way, to help the absorption and utilization of the nutrient of interest or to aid in the way it protects the body from damage.

Treatments which are effective at reducing the fluid leakage beneath the retina, or in controlling the proliferation of blood vessels in the retina, might also be effective in the treatment of the fluid leakage and blood vessel proliferation that occurs in VHL. Clinical trials of these agents are beginning to open this year.

For the carotenoid levels of foods, and other nutritional hints, see www.vhl.org/nutrition

Addendum from Altheada:

It is suggested that people supplement their diets with 4 mg of lutein/zeaxanthin daily, however it is very easy to get it from food. Food provides other phytochemicals that might act in a synergistic way, to help the absorption and utilization of the nutrient of interest or to aid in the way it protects the body from damage. In addition, food offers who knows what other benefits.For example, kale is probably one of the best sources of lutein/xeazanthin. Kale contains 39,550 micrograms of lutein/zeaxanthin per 100 grams edible portion. One cup chopped kale is 67 grams, so to get to the 100 grams, you would need to eat about a cup and a half of chopped raw kale. That's not an unrealistic amount, because this is a cup of loosely packed greens, not packed tightly into a measuring cup. One and one half cups would probably result in about 3/4 cup once cooked because this type of green wilts when cooked.

If you do the conversion, 39,550 micrograms is 39.55 mg of lutein/zeaxanthin or roughly ten times the amount researchers recommend that people take as a supplement! Therefore, you can eat just a few leaves and easily get 4 mg of lutein.Broccoli contains 2,445 micrograms of lutein/zeaxanthin per 100 grams edible portion. One cup chopped (raw) is about 88 grams, so you would need to eat slightly more than a cup to get 2.5 mg of lutein/zeaxanthin.

Finally, spinach has 11,938 micrograms per 100 grams. A cup and a half (roughly 100 grams) will give almost three times the amount of lutein recommended. Here, a very manageable 1/2 cup per day would meet the amount suggested.

As printed in the VHL Family Forum  12:1, March/April 2004.  For permission to reprint, please contact VHL Family Alliance, editor@vhl.org. Further information is available from the VHL Family Alliance, info@vhl.org.