Corneal thickness affects SLT efficacy, surgeon says

Central corneal thickness has an effect on the efficacy of selective laser trabeculoplasty, according to one surgeon.

Just as central corneal thickness affects the accuracy of IOP measurements by Goldmann applanation tonometry, said Karanjit Kooner, MD, it can also affect the outcome of selective laser trabeculoplasty (SLT), providing greater pressure-lowering effect in thinner corneas.

Dr. Kooner said he often uses SLT in eyes with thinner corneas to achieve lower target pressures, and he wondered if these eyes had a preferential response to SLT. He and colleagues at the University of Texas-Southwest in Dallas retrospectively analyzed 81 eyes of 53 patients with glaucoma who had previously undergone both SLT and measurement of central corneal thickness. The mean age of the patients was 66.5 years old.

Dr. Kooner described his technique and the results of his study in the Sept. 1 issue of Ocular Surgery News.

“Our approach to SLT treatment is to perform a full 360° treatment in one setting, with average power of 0.8 mJ,” he said. He then titrates the power up or down to get just a few fine “champagne bubbles” with most shots. Most eyes in the series received 100 treatment spots or less, and all patients were treated with topical steroids for 5 to 7 days “to suppress the mild anterior chamber reaction that often occurs” after SLT, he said.

SLT was effective in lowering IOP in the study population, with an average drop in IOP of 2.9 mm Hg from baseline. Eyes with thinner corneas had more of a reduction than those with thicker corneas, he said. The number of glaucoma medications was significantly reduced from baseline in the patients who underwent SLT as well, he said.