Vision Not Improved By Surgery for Complications of Age-Related Macular Degeneration

Vision does not improve substantially for patients with age-related macular degeneration (AMD) who undergo surgery to remove lesions of new blood vessels, scar tissue, or possible bleeding beneath the retina, according to results of nationwide clinical trials sponsored by the National Eye Institute (NEI), part of the National Institutes of Health.

In older adults, the most common cause of irreversible and severe loss of vision is called wet AMD. Unwanted blood vessels and scar tissue grow beneath and into the macula, the central part of the retina responsible for perceiving fine visual detail. Treatment options for improving vision are limited for wet AMD.

The NEI-funded Submacular Surgery Trials (SST) investigated outcomes of surgery being practiced by retinal surgeons to remove lesions–scientifically known as choroidal neovascularization–that are linked with AMD and other causes. Before the trials began in 1997, the risks and benefits of surgery to improve or stabilize vision of patients with such conditions had not been well defined.

“While the trials were not successful in doing what we wanted to do for these patients with AMD, that is, to keep their vision stable or to improve it,” says NEI Director Paul A. Sieving, M.D., Ph.D., “the study provides valuable information to doctors and their patients. But, we will not stop there. The NEI will continue to conduct and support the best research possible while the search continues for new effective treatments for AMD,” Sieving added.

In the November issue of the journal Ophthalmology, four of a total of six main result papers on the SST will be published. The four papers address surgery for two groups of AMD patients.

In the first group, surgery did not improve vision for half of 454 patients who had centrally located lesions that were not predominantly blood, when compared with half who did not receive surgery but did receive regular eye examinations. This finding confirms a growing clinical impression among many retinal surgeons that submacular surgery is not helpful for these commonly-found lesions in AMD patients’ eyes.

Surgery was also not beneficial for a second group of patients–those with more extensive bleeding under the retina. This second group involved 336 patients who were assigned randomly to either surgery or careful observation. Among these patients, vision had not stabilized or improved after two years in those who underwent surgery to remove lesions and associated blood (which was the primary test of the trials), when compared with patients with no surgery.

Other treatments for CNV due to AMD include laser photocoagulation and photodynamic therapy. Both laser photocoagulation and photodynamic therapy have been shown to reduce the risk of moderate and severe loss of vision in some patients with CNV associated with AMD. But these treatments usually are not used for eye lesions similar to those of patients who took part in the SST.

According to estimates published by the NEI-sponsored Age-Related Eye Disease Study, approximately 200,000 individuals in the United States develop the wet, or neovascular, form of AMD each year. This form occurs in less than 20 percent of all patients with AMD but is responsible for approximately 90 percent of cases with severe vision loss.

The SST built on an hypothesis (emanating from earlier NEI-sponsored SST pilot studies) that surgical removal of CNV lesions may halt enlargement of the visual defect. Further, their removal might spare vital photoreceptors in the central macula from damage and thereby allow nearby ocular structures to function normally.

Patients in the trials also answered questionnaires and surveys to record how their eye condition affected their quality of life, before and after the surgery. Not surprisingly, SST patients reported a high degree of quality of life impairment due to poor vision.

A total of 25 clinical centers collaborated in the trials for the AMD patients with CNV. Two other SST papers, on surgery for CNV due to two causes other than AMD, will be published in the November 2004 Archives of Ophthalmology. The target conditions for those papers were CNV caused by ocular histoplasmosis syndrome or by unknown causes (idiopathic).