Dr. Marla Shapiro: Age related macular degeneration
Dr. Marla Shapiro, Canada AM health and medical expert
Published Tuesday, January 22, 2013 7:40AM EST
Age related macular degeneration is the # 1 cause of loss of sight in people over age 65 and older. The macula is the part of the retina that gives us our sharp vision.
There are 2 kinds of macular degeneration- wet and dry. Wet means there are vascular changes- meaning therr are blood vessels that grow where they should not be. Dry is more commin than wet but wet is more serious. We do know that vitamins such as beta carotene, C and E can slow down dry macular degeneration as well as zinc and lutein.
Risk factors for ARMD include aging, smoking, a family history. High blood pressure, lighter eye colour and obesity. It is also thought UV exposure may be a risk factor too. Genetics and inheritance of an abnormal gene account for ARMD as well.
In this week's JAMA is a study reporting on an association between regular use of ASA and a 2.5 fold greater risk of AMD- wet form. The question is whether this is cause and effect or whether this is merely an association.
Potential explanations according to an editorial in the Journal include that AsA can supress processes leading to low oxygen and possible bleeds in the retina. The critique is quick to point out that we cannot conclude there is a cause and effect relationship.
So where does this lead us? As always it is important to make sure the benefit of a medication outweighs potential risk. So on cases of secondary prevention where ASA is clearly indicated, there is no basis to change its usage.
Current Canadian guidelines for ASA are clear that there is no proven role in primary prevention. One has to weigh the other risk factors for ARMD individually and make decisions about ASA usage.