Selective Laser Trabeculoplasty: adverse effects of prior topical anti-glaucoma medication

Abstract

Purpose : To determine the long-term effects of prior topical anti-glaucoma medications and other potential risk factors for failure on Selective Laser Trabeculoplasty (SLT).

Methods : The results of 264 SLT procedures (127 patients), performed over 10 years were assessed in a single surgeon, observational, cohort study. The absolute number of anti-glaucoma drops administered into individual eyes prior to SLT therapy was determined from clinical records. Other potential risk factors assessed were age, gender, pre-SLT intraocular pressure (IOP) and SLT energy. Complete success was defined as a 20% reduction in IOP without the requirement of topical anti-glaucoma therapy and partial success with or without such therapy. Kaplan Meier survival curves were plotted relating to the risk factors. A multivariate Cox’s proportional hazards regression (HR) analysis was performed to account for cases with more than one risk factor.

Results : Mean (±SD) follow-up was 4.8±2.9years. Mean immediate pre-SLT IOP was reduced from 22.4±4.6mmHg (on 0.9±1.2drops) to 16.8±5.1mmHg (p<0.0001) on 0.6±1.0 drops at 2 months post-SLT and to 18.4±2.5mmHg (p<0.0001) on 0.7±1.1 drops at the final visit. For both complete and partial success, a greater number of drop administrations (assuming 100% adherence) was identified as a risk factor for failure(Chi²=92.3, p<0.0001 & Chi²= 18, p=0.0004 respectively). For complete success, eyes with the greater number of drops administered (>7392) were at the highest risk of failure (HR 3.55; 95% CI: 2.3-5.4, p<0.0001). Higher age was predictive of SLT failure for both complete and partial success (Chi²=17.5, p=0.0006 & Chi²=16.2, p=0.001 respectively). A higher pre-SLT IOP was associated with a greater probability of both complete and partial success (Chi²=27.7, p<0.0001 & Chi²=34.7, p<0.0001 respectively). For partial success, a lower SLT laser energy used was associated with a greater chance of failure (Chi²=7.97, p=0.047). Gender appeared to have no effect on SLT outcome.

Conclusions : Long-term exposure to topical anti-glaucoma medication before SLT treatment may have an adverse effect on outcome. Higher age was identified as a risk factor for failure, whilst a higher pre-SLT IOP was associated with a greater chance of success. A lower (inadequate) level of SLT energy delivered may be a significant relative risk factor for failure.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.