Vitamin A: A Role in Macular Degeneration and Fractures

Q:  I am 65 years old. Because both of my parents have Age Related Macular Degeneration (ARMD) and I have developed drusen, my ophthalmologist suggested that I take an "eye vitamin." Since Bausch & Lomb had just published their study on the treatment of ARMD, I decided to take their Ocuvite PreserVision. The dosage in the daily four tablets is 28,640 IU of Vitamin A.

When I called Bausch & Lomb, they said that because they use beta-carotene in their formula, too much Vitamin A was not a problem, but in a recent article you indicated that Vitamin A in any form leads to decreased bone density. It sounds like I am trading the possibility of forestalling ARMD for an increased risk of hip fracture. Is this correct?

A:  First, let me explain macular degeneration for our readers who aren't familiar with the condition. The macula is a very sensitive area located in the center of the retina. The retina, of course, is the tissue at the back of the eye that converts the light and images we see into electrical impulses and sends these nerve signals to the brain, where we interpret them visually. Macular degeneration refers to the deterioration of the macula, which can lead to vision loss.

Age Related Macular Degeneration (ARMD) occurs in two forms: dry and wet.

Dry ARMD occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye. As dry ARMD gets worse, you may see a blurred spot in the center of your vision. Over time, as less of the macula functions, central vision in the affected eye can be lost gradually. You may notice you have difficulty recognizing faces, or need more light for reading and other tasks. Dry ARMD generally affects both eyes, but vision can be lost in one eye while the other eye seems unaffected. One of the most common early signs of dry ARMD is drusen. Drusen are yellow deposits under the retina. They often are found in people over age 60. Your eye care professional can detect drusen during a comprehensive dilated eye exam.

Wet ARMD occurs when abnormal blood vessels behind the retina start to grow under the macula. These new blood vessels tend to be very fragile and often leak blood and fluid. The blood and fluid raise the macula from its normal place at the back of the eye. Damage to the macula occurs rapidly.

With wet ARMD, loss of central vision can occur quickly. Wet ARMD is an advanced form of the condition and is more severe than the dry form. An early symptom of wet AMD is that straight lines appear wavy. If you notice this condition or other changes to your vision, contact your eye care professional at once. You need a comprehensive dilated eye exam.

The study you're referring to was a large clinical trial of macular degeneration that included people aged 55-80 years. Among participants with at least intermediate ARMD (medium-sized drusen in both eyes or one or more large drusen in one or both eyes), this study found that taking four daily Ocuvite tablets for an average of six years reduced the risk of progressing to advanced ARMD by about 25%. One Ocuvite contains 500 mg of Vitamin C, 400 IU of Vitamin E, 15 mg of beta-carotene (7,160 IU of Vitamin A), 80 mg of zinc and 2 mg of copper.

Your dilemma is a good example of balancing competing risks in preventive care. It helps to remember that research studies report a risk percentage that applies only to the average participant in their study. For instance, if you only have mild ARMD or only a family history of ARMD, the Ocuvite will likely not help slow progression. The reported 25% benefit applies only if you are in the age range of the study participants, have intermediate ARMD and take four Ocuvites every day for six years.

Similarly, the research showing that osteoporotic fractures increased 50% in women with high intakes of Vitamin A studied nurses aged 34-77 years, on average somewhat younger than you.

You can assess your personal risk of osteoporosis by getting a bone mineral density test. If you have intermediate ARMD and reasonable bone mineral density, you may choose to take Ocuvite because your hip fracture risk would be low. If you have osteoporosis and only small drusen, you may choose to skip the Ocuvite and take steps to reduce chances of hip fracture.

This article includes information from the National Eye Institute.

For more information on this topic, see the HealthLink articles Research Focuses on Age-Related Macular Degeneration and Treatment Options for Age-Related Macular Degeneration.

Julie L. Mitchell, MD, MS, is an Assistant Professor of Medicine at the Medical College of Wisconsin. She practices internal medicine at the Froedtert & Medical College General Internal Medicine Clinic - East. Her column also appears in the Milwaukee Journal-Sentinel.