For a 20% reduction in IOP with or without the requirement of topical glaucoma treatment, a lower SLT laser energy used was associated with a greater chance of failure. Photo: Nate Lighthizer, OD. Click image to enlarge.

Laser therapy in glaucoma, particularly selective laser trabeculoplasty (SLT), is becoming more and more embraced as a first-line treatment. When used as adjunctive therapy, it pairs well with most glaucoma drugs. However, new findings have elucidated that the timing of medications for the condition can bring about risky results. Researchers based out of the Norfolk and Norwich University Hospitals NHS Foundation Trust in the UK have determined that continued exposure to topical glaucoma medication for an extended period before the SLT procedure may have an adverse effect on outcome. A greater number of drop administrations (assuming 100% adherence) was identified as a risk factor for failure. This study was presented at the ARVO meeting in Seattle on Monday.

To determine the long-term effects of prior topical anti-glaucoma medications and other potential risk factors for failure on SLT, the research team assessed the results of 264 procedures (127 patients) performed over 10 years. They also used clinical records to establish the absolute number of anti-glaucoma drops administered into individual eyes prior to SLT treatment. Complete success was defined as a 20% reduction in IOP without the requirement of topical glaucoma therapy and partial success with or without such therapy. In the patient cohort, the mean follow-up was 4.8 years.

Mean immediate pre-SLT IOP was reduced from 22.4mm Hg (on 0.9 drops) to 16.8mm Hg on 0.6 drops at two months post-SLT and to 18.4mm Hg on 0.7 drops at the final visit. For complete success, the researchers noted that eyes with the greater number of drops administered (greater than 7,392) were at the highest risk of failure (hazard ratio: 3.55). A higher age was predictive of SLT failure for both complete and partial success, while a higher pre-SLT IOP was associated with a greater probability of both complete and partial success. Patient sex appeared to have no effect on the SLT treatment outcome.

The researchers also highlighted that, for partial success, a lower (or inadequate) SLT laser energy used was associated with a greater chance of failure.

Original abstract content ©2024 Association for Research in Vision and Ophthalmology.