Complications of AMD Trial (CAPT) Results Announced

You may have heard about the recent article in the journal Ophthalmology about the Complications of AMD Trial or CAPT for short. This trial involved 1052 people who had at least 10 large drusen in both eyes. They were randomized to receive light laser treatment to one eye only. There were 22 clinical centers that performed the study. I was the principal investigator of this study at the The University of Iowa center. My colleagues, Drs. Boldt, Gehrs, and Russell were also investigators. The patients in this study were followed for at least five years and in many cases, six years after the laser treatment.

The result of the study showed that there was no difference between the eyes that were treated with laser when compared to the eyes that were not treated. There was no difference in the visual acuity, the risk of developing new blood vessels (wet AMD), or the risk in developing atrophy from dry AMD.

You may ask why did we ever think that laser could help? Well, drusen are collections of many different molecules beneath the retinal pigment epithelium. Drusen increase the distance between the RPE and the nourishing capillaries in the choroid. They may also impede the flow of nutrients. We thought therefore, that the photoreceptors, which are nourished by the RPE, might suffer and even die especially in areas of thick drusen. In fact, areas of atrophy often develop directly over large drusen. We also thought that the photoreceptors and drusen might produce molecules to attract new blood vessels because they weren’t getting enough oxygen and nourishment and that this could be a cause of wet AMD.

For these reasons, we believed that if we reduced the number and extent of drusen, this may help to preserve vision in AMD. Unfortunately it didn’t seem to make a difference. Therefore laser treatment for the sole purpose of getting rid of drusen is not advisable.

The 1052 patients in CAPT were followed closely. We collected a lot of information on each patient and performed color photography and fluorescein angiography on a yearly basis. CAPT contains a wealth of information that many doctors and statisticians are reviewing right now. This information will give us insights into the cause and course of AMD. So stay tuned!

Reference:
Laser Treatment in patients with bilateral large drusen. The Complications of Age-Related Macular Degeneration Prevention Trial Research Group. Ophthalmology. 2006; 113(11):1974-1986