A retrospective study conducted at Wills Eye Hospital in Philadelphia has determined that greater pre-selective laser trabeculoplasty (SLT) IOP and greater angle pigment grading positively correlated with SLT success.

The researchers assessed 997 eyes in 677 patients who received SLT. They defined SLT success as an IOP decrease ≥ 20% from baseline at the three-month, six-month and 12-month follow-up visits. They considered SLT to have failed when eyes needed additional SLT or glaucoma surgery. SLT success was achieved in 227 (22.8%) eyes, while 770 (77.2%) failed to meet success criteria.

On average, pre-SLT IOP was 21.9±5.2mmHg with 2.0±1.2 medications in eyes with successful SLT, compared with 19.0±5.0mmHg and 2.1 ±1.3 medications in eyes with SLT failure. At the one-year follow-up, the mean IOP in successful SLT eyes was 14.7±3.2mmHg with 2.0±1.2 medications, while eyes with SLT failure had 16.3±4.7mmHg with a mean of 1.9 ±1.3 medications. Eyes with SLT success more often had greater angle pigment grading, while SLT failures had less angle pigmentation.

The researchers found no positive correlation with age, glaucoma severity, total SLT power, type of glaucoma, severity of glaucoma, visual field mean defect and RNFL thickness. There was also no difference between the rate of success based on pre-SLT treatments, whether surgical or medical.