Cataract Surgery Does Not Appear to Make Age-Related Macular Degeneration Worse

Editorial says more research is needed; patients should be briefed on all study findings

Nov. 9, 2009 - Age-related macular degeneration (AMD), the leading cause of blindness among senior citizens, does not appear to progress at a higher rate among individuals who have had surgery to treat cataract, the leading cause of blindness worldwide among all ages. The study challenges previous reports that treating one cause of vision loss worsens the other.

Surgery is the most effective and common vision-restoring treatment for cataract.

"Because both conditions are strongly age-related, many individuals with cataract also have AMD," the authors write.

"There has been a long-standing controversy among clinicians as to whether cataract surgery is contraindicated in eyes with non-neovascular AMD. A major concern has been whether cataract surgery increases the risk of progression to neovascular AMD [an advanced form of the disease involving formation of new blood vessels] in eyes at risk of progression such as those with intermediate AMD," the researchers write in the November issue of Archives of Ophthalmology, one of the JAMA/Archives journals.

Li Ming Dong, Ph.D., of Stony Brook University School of Medicine, N.Y., and colleagues studied eyes of 108 individuals with non-neovascular AMD who underwent preoperative assessments for cataract surgery between 2000 and 2002.

Photographs of the retina were taken and fluorescein angiography, which uses a special dye to investigate blood vessels in the eye, was performed.

A total of 86 evaluated eyes had non-neovascular AMD before surgery, and 71 had follow-up assessments between one week and one year after surgery.

Neovascular AMD was observed in nine (12.7 percent) of these 71 eyes at one or more follow-up assessments.

Five eyes displayed signs of neovascular AMD at the one-week follow-up point; the size and location of the lesions identified indicated that they may have been present before surgery but not visible due to the opaque lens caused by cataract. When these eyes and one eye that did not have one-week follow-up photographs available were excluded, the progression rate between one week and one year decreased to three of 65 eyes (4.6 percent).

The rate of progression to neovascular AMD was similar among participants' other, cataract-free eyes over the same time period (one eye, or 3 percent).

"Our findings suggest that previous reports of the association or progression of non-neovascular AMD to advanced AMD after cataract surgery could be biased with the absence of immediate pre-operative and postoperative fluorescein angiography to rule out pre-existing neovascular AMD or geographic atrophy," the authors write.

"Subtle signs of neovascular AMD or geographic atrophy, even on an angiogram, may be obscured by lens opacity just prior to cataract surgery. In such cases, the neovascular disease or the geographic atrophy may contribute to the individual's vision loss, and this may erroneously be ascribed to the cataract and contribute to a decision to proceed with cataract surgery."

"Our findings do not support the hypothesis that cataract surgery accelerates the progression of AMD," they conclude.

Editorial Says More Research Needed to Illuminate Potential Link

"Since the late 1980s, there have been several reports of an association between cataract surgery and age-related macular degeneration," writes Barbara E. K. Klein, M.D., M.P.H., of the University of Wisconsin-Madison, in an accompanying editorial.

"Some report a cross-sectional association; some, incidence of AMD after surgery; and yet others report progression to more severe AMD.

“Still, there are some studies that do not find a significant association after controlling for relevant confounders. What might explain the disparate results?

“In my estimation, the diversity of findings in no small part begins with differences in study design."

Until an ideal study is designed to examine the associations, clinicians will still have to answer difficult questions from patients regarding cataract surgery, Dr. Klein notes.

"A straightforward discussion of the inconsistencies of the research findings to date regarding risks of progression of early AMD and development of late AMD and its accompanying risk of severe loss of acuity after cataract surgery would help both the patient and his or her physician to make a more informed decision," she concludes.

"Until we have better information regarding the risk of developing AMD in those undergoing cataract surgery, it is the best we can do for our patients."

Editor's Note: This editorial is supported by a National Institutes of Health grant and, in part, by Research to Prevent Blindness.