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IOP decrease after trabeculectomy may slow or reverse rate of visual field decay
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NEWPORT, R.I. — Clinical observation of visual sensitivity improvement after a robust decrease in IOP is not a rare phenomenon, nor is such improvement a new idea, according to a speaker.
Joseph Caprioli, MD, added support to the observations with study results at the American Ophthalmological Society meeting, hypothesizing that retinal ganglion cells may be “sick but not dead” and that pressure reduction with trabeculectomy in patients with open-angle glaucoma may not only slow the rate of glaucomatous visual field damage, but also reverse it.
“Our approach here was to measure change in rates at each individual test location before and after trabeculectomy,” Caprioli said of the long-term study that allowed for decay or improving rates. Caprioli and colleagues studied 74 eyes of 65 patients with open-angle glaucoma before and after trabeculectomy and used a comparison group of 71 eyes of 55 patients with similar damage but deemed clinically stable to help address difficulties in long-term fluctuations and possible regression to the mean.
“This is not a control group to compare treatment and no treatment,” he said.
The main result of the study showed that in patients in the trabeculectomy group whose visual fields were declining before surgery, the rate of decline flattened after surgery. In the comparison group, visual fields continued to decline at a relatively slow rate. In the trabeculectomy group, 80% of eyes improved postoperatively in five or more test locations compared with preoperative values, and 57% of eyes improved in 10 or more test locations.
“There’s a big difference between the trabeculectomy group and the comparison group in this regard,” Caprioli said.
In multivariate analysis for improvement in the trabeculectomy group, only change in IOP was significantly associated with the number of points that improved postoperatively, Caprioli said. - by Patricia Nale, ELS
Disclosure: Caprioli reports financial interests and relationships with Alcon, Allergan, New World Medical, Transcend, National Institutes of Health/National Eye Institute, Research to Prevent Blindness and Simms/Mann Foundation.