Immunosuppressive Therapy Diminishes Long-Term Laser Trabeculoplasty Efficacy

Patients using immunosuppressive therapy can experience diminished long-term response to selective laser trabeculoplasty (SLT) treatment, despite an equivalent early reduction in intraocular pressure (IOP), according to findings published in the Journal of Glaucoma.

Because researchers believe SLT reduces IOP through a mechanism of systemic immune activation, the study evaluated the short-term and long-term efficacy of SLT in patients undergoing immunosuppressive therapy and compared them with immunocompetent controls. The researchers retrospectively evaluated data from 2105 eyes of 1489 patients in Minnesota, Arizona, and Florida. The immunosuppressive therapy group (n=108 eyes, 72 patients) included patients who were receiving at least 1 systemic immunosuppressive therapy at the time of the SLT procedure.

The control group consisted of an older population compared with the immunosuppressive therapy group (74.0±11.9 vs 70.7±10.6 years; P <.001) but the groups were otherwise similar. Compared with age-matched controls, there was no significant difference in the short-term percent reduction of IOP (1 to 2 months post-SLT). At 3 to 6 months post-SLT, there was a trend toward greater IOP reduction in the control group compared with the immunosuppressive therapy group, but this association was not significant. (-18.3±23.2 vs -15.2±21.6%; P =.062). 

At 12 months post-SLT, IOP reduction was significantly greater in the control group compared with the immunosuppressive therapy group (-20.3±22.9 vs -15.1±21.2%; P =.045). Subgroup analysis was performed to evaluate the influence of steroid-induced IOP on the results. However, there was no difference between patients in the immunosuppressive therapy group with or without concurrent systemic steroid use at each time point.

Because the number of post-SLT interventions were similar, the authors concluded that these results support the hypothesis that immunosuppression during SLT alters IOP regulation. To explain the data, the authors propose several mechanisms. 

“Our data may lead one to generate several potential hypotheses to explain the data. Possibilities include a true late diminished therapeutic effect from SLT, early loss of therapeutic effect, or perhaps a yet unexplained alteration in IOP regulation separate from SLT related to systemic immunosuppressive medications or the underlying autoimmune or inflammatory disease,” the researchers explain. “While this study is unable to confirm or reject a particular immune-mediate pathway involved in the IOP-lowering effect of SLT, the differences in IOP between groups suggests that the immune system does play a role in IOP regulation in patients who underwent SLT.”

The study was limited by unbalanced population sizes and variable practice patterns due to vague standards to when to perform SLT or subsequent therapies.