A long-term study has shown that selective laser trabeculoplasty (SLT) significantly reduces glaucoma progression and vision loss when compared to traditional eye drop therapy. Results from a large randomized trial indicate that after six years of follow-up, patients treated with SLT experienced a 29% lower rate of glaucoma progression than those treated with eye drops.
The study, presented by Dr. Giovanni Montesano of Moorfields Eye Hospital in London at the American Academy of Ophthalmology conference, revealed that patients who started treatment with eye drops had more than double the rate of fast glaucoma progression. Additionally, ultra-fast progression occurred three times as often in the eye drop group compared to the SLT group. This difference was observed despite both treatment groups being managed to the same intraocular pressure (IOP) targets.
“If you achieve a predefined target IOP based on the severity of the disease, further studies are needed to understand how different treatments impact visual field progression,” said Montesano. “It’s not just about the pressure or target IOP, but how we achieve that pressure can make a difference.”
Questions About Eye Drops and Treatment Adherence
During the presentation, audience members raised questions about whether the type of eye drop used could influence the results, with some asking about the differences between beta blockers and alpha agonists. While Montesano acknowledged that the research team has data on the specific eye drops used, they have yet to analyze the impact of different medications.
Another question raised was whether quality of IOP control over a 24-hour period might have affected the outcomes. Montesano stated that while this data is available, it has not yet been explored in the analysis.
Some participants also speculated whether adherence to eye drop therapy might explain some of the differences between treatment outcomes. Montesano agreed that compliance could be a factor, as poor adherence to drops may lead to inconsistent pressure control throughout the day or night, which could affect the visual field.
Dr. John Lind, the session’s moderator, pointed out that the investigators focused on mean deviation from the target IOP as an endpoint. He noted that cataract development, among other factors, could affect this measurement. Montesano responded that while cataract might confound results, the team found no significant difference in cataract occurrence between the two groups.
Historical Context
Traditionally, glaucoma and ocular hypertension have been treated with pressure-lowering eye drops. SLT, introduced in 1995 and FDA-approved in 2001, offers an alternative treatment by reducing ocular pressure through a single outpatient procedure. This procedure increases aqueous outflow via the trabecular meshwork in the eye.
The randomized phase III LiGHT trial, comparing SLT to eye drops, began to yield results at the 36-month mark. At that time, no significant difference in health-related quality of life was found between the two treatments. However, three-quarters of the patients in the SLT group had not required eye drops to control their IOP. Additionally, patients in the SLT group had fewer clinic visits and none required glaucoma surgery, while 11 patients in the eye drop group did. A cost-effectiveness analysis also showed that SLT had a 97% probability of being cost-effective at a threshold of £20,000.
Six-Year Results: SLT Proves Superior
Dr. Montesano presented the findings from six years of follow-up in the trial. The study involved 718 patients with newly diagnosed open-angle glaucoma (OAG) or ocular hypertension. Patients were eligible if their visual field loss was no worse than -12 dB in the better eye and -15 dB in the worse eye. Both eyes received identical treatment if affected.
Using advanced statistical techniques that separated median deviation rates from noise and learning effects, investigators calculated the “true” median deviation rate of visual field progression. The baseline median deviation rate was -2.15 dB for the SLT group and -2.13 dB for the eye drop group.
After six years, the SLT group showed a significantly slower progression rate, with a median deviation rate of -0.26 dB per year, compared to -0.37 dB per year in the eye drop group (P=0.006). When fast progression was defined as a rate worse than -0.50 dB/year, twice as many eye drop patients met this criterion (25.4% vs. 14.4%). With a very fast progression cutoff of -1.0 dB/year, three times as many eye drop patients experienced rapid vision loss (6.5% vs. 2.1%).
Conclusion
The findings from this trial suggest that SLT should be considered an effective and safe first-line treatment for primary open-angle glaucoma. In addition to lowering intraocular pressure, SLT also offers a potential advantage in reducing vision loss and slowing disease progression compared to conventional eye drop therapy.
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