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Study suggests neuroprotective action for brimonidine
Brimonidine preserved visual fields better than argon laser trabeculoplasty in a prospective clinical study in glaucoma patients, despite lower IOPs achieved in the eyes undergoing ALT. This finding suggests that the drug has neuroprotective properties beyond IOP-lowering, according to the first author of the study.
Stefano Gandolfi, MD, and colleagues at London’s Moorfields Eye Hospital compared the results of treatment with brimonidine and treatment with ALT in the masked, prospective, randomized study. Dr. Gandolfi has presented results of the study at a number of meetings this year, including the Association for Research in Vision and Ophthalmology meeting and the European Glaucoma Society meeting.
Dr. Gandolfi said brimonidine’s potential neuroprotective properties have been suggested by laboratory studies. This is the first trial in humans to suggest such an effect, he said.
Study design
Patients were eligible for participation if they had a glaucomatous visual field defect; visual acuity better than 0.2 LogMAR; a refraction of between –5 D and +2 D; no presence of age-related macular degeneration, diabetic neuropathy or other neurological disease; and IOPs of 20 mm Hg or greater, Dr. Gandolfi said.
Prior to randomization, patients underwent an 18-month observation period, during which they were observed for changes in VA and progression of visual field defects. Once progression of damage was confirmed, patients were then randomized to receive treatment with either 360° ALT or 0.2% brimonidine twice daily. Progression was detected in 52 eyes.
If a drop in IOP of at least 10 mm Hg was not seen in an eye after randomization, that eye was switched to the other treatment. After the switching, 50 eyes qualified for follow-up: 29 on brimonidine and 21 with ALT.
A total of 41 eyes completed follow-up, 22 that had been treated with brimonidine and 19 with ALT.
At 18 months follow-up, patients treated with ALT had lower mean IOP than those treated with brimonidine (14.6 mm Hg vs 15.7 mm Hg respectively).
However, Dr. Gandolfi noted, significantly fewer patients treated with brimonidine than with ALT experienced progression of visual field deterioration. Among the brimonidine-treated patients, 17 had stable visual fields and two had progression of damage.
Eleven ALT patients continued to show progressive visual field loss, despite the group in general having better IOP control than the brimonidine-treated patients, he said.
“In essence, the effect of brimonidine in visual field progression cannot just be explained by the pressure decrease,” Dr. Gandolfi said.
Future work
In an interview, Dr. Gandolfi said brimonidine and ALT might work well together in some patients.
“Why not?” he said. “ALT works on trabecular outflow, and meanwhile brimonidine is active via a decrease in inflow and a late-onset increase in uveoscleral outflow.”.
For Your Information:
- Stefano Gandolfi, MD, can be reached at the Univ Eye Clinic, Via Gramsci 14, 43100 Parma, Italy; +39-0521-703097; fax: +39-0521-994820; e-mail: s.gandolfi@rs.rsadvnet.it.
- Jeanne Michelle Gonzalez is an OSN Staff Writer, who specializes in practice management, regulatory and legislative topics, in addition to cataract and refractive surgery.