Repeat-selective laser trabeculoplasty (SLT) administered during the LIGHT Trial lowered intraocular pressure (IOP) in eyes with IOP increases during 1.5 years after the initial SLT application. The decrease lasted longer than the initial lowering.
This article was reviewed by Prof Gus Gazzard, FRCOpthMA, MBBCHIR, MD
Repeat-selective laser trabeculoplasty (SLT), a protocol explored in a subset of patients in the SLT Laser in Glaucoma and Ocular Hypertension (LIGHT Trial), successfully lowered the IOP in eyes in which the IOP increased after 1.5 years after the initial SLT application.
The IOP decrease resulting from repeat-SLT lasted longer than the first round of IOP lowering.
The three-year LIGHT Trial evaluated the initial treatments using SLT laser or medications in patients with glaucoma and ocular hypertension; treatments were increased as required, according to Gus Gazzard, FRCOpthMA, MBBCHIR, MD, professor of ophthalmology at UCL-University College and consultant ophthalmic surgeon, Moorfields Eye Hospital, London.
The study included only treatment-naïve patients with newly diagnosed primary open-angle glaucoma (POAG) or ocular hypertension in one or both eyes. Patients with advanced disease who could not be treated with laser or medication were excluded from the trial.
A total of 718 patients ultimately were randomly selected to either SLT laser or medication at the beginning of the LIGHT Trial.
At the end of the three years, 91% of patients remained in the study.
The initial standardized SLT protocol included 360º of treatment in which 100 laser shots were applied using a Latina SLT contact lens.
The clinical endpoint was that at least 50% of the shots had visible bubble formation without free streams of bubbles. The SLT could be repeated once, Dr. Gazzard explained.
The criteria for undergoing repeat-SLT were failure within 18 months after the initial SLT and eyes in which retreatment was triggered at a pre-defined criteria using eye-specific, severity-dependent target IOP, and/or disease progression based on a custom-designed clinical decision-support algorithm.
That software also guided the follow-up intervals and time to reintervention.
In selecting the eyes to undergo repeat-SLT, the investigators also considered the degree of IOP lowering at two months; this value at that time point is strongly predictive of the three-year outcome.
The two-month time point was the first time point at which treatment increases were allowed.
The investigators also looked at the duration of the effect after the initial and the repeated applications of SLT to determine how long the target IOP remained controlled, Dr. Gazzard explained.
In the initial LIGHT Trial, 611 eyes underwent SLT. Of those, 158 eyes failed during the first 18 months and 115 eyes (90 patients) underwent repeat-SLT.
The other 43 eyes that were not at the target IOP did not undergo repeat-SLT.
“The total repeat-SLT power used was slightly greater,” Dr. Gazzard reported.
The initial value was 89.1 mJ versus 100.5 mJ, which was a significant increase (p < 0.001).