In Advanced Glaucoma, Trabeculectomy Lowers IOP More Than Medication

NEW YORK (Reuters Health) – Patients with advanced glaucoma who undergo primary trabeculectomy have lower intraocular pressure (IOP) and similar safety and quality-of-life outcomes as those who receive medical management, according to a randomized trial from the U.K.

“No serious sight loss associated with surgery was found, quality of life was equivalent between the medical and surgical interventions, and there was no material progression in glaucoma during the study period in either group,” Dr. Anthony J. King of Nottingham University Hospital told Reuters Health by email.

Even though “advanced glaucoma at presentation is the biggest risk factor for lifetime blindness, clinicians are reluctant to undertake primary surgery because of concerns about surgical complications and lack of evidence,” Dr. King and his colleagues write in The BMJ. “This study provides the first direct evidence of the outcomes of interventions for patients presenting with advanced glaucoma.”

Over three years, the research team enrolled 453 patients newly diagnosed with advanced open-angle glaucoma in the pragmatic TAGS trial, which took place at 27 hospitals in the U.K. Investigators randomly assigned 227 patients to receive mitomycin C-augmented trabeculectomy and 226 to receive escalating medical management with IOP-reducing drops.

The patients’ mean age was 68 years and 67% were male. Both treatment groups had a mean baseline Visual Function Questionnaire-25 (VFQ-25) score of 87.1. Patients unable to undergo incisional surgery or at high risk of trabeculectomy failure were excluded.

At 24 months, the mean VFQ-25 score was 85.4 in the trabeculectomy group and 84.5 in the medical management group (P=0.38).

The mean IOP for trabeculectomy patients was 12.4 mmHg versus 15.1 mmHg for those on medical management (P<0.001).

At 24 months, both groups had similar results in the EuroQol Group’s five-dimension five-level health-status questionnaire (EQ-5D-5L), the Glaucoma Utility Index (GUI) and the Health Utility Index-mark 3 (HUI-3).

Eighty-eight patients in the trabeculectomy group (39%) experienced adverse events, compared to 100 (44%) in the medical management group (P=0.37); 12 trabeculectomy patients and eight medically managed patients had a serious adverse event (P=0.38).

One participant in each group developed endophthalmitis, and three in the trabeculectomy group lost more than 10 letters of logMAR visual acuity due to progressive glaucoma or central serous retinopathy.

“Limitations include the fact that treatments and patient reported outcome measures could not be masked from participants or clinicians,” the researchers note, as well the fact that most participants were white, which may limit the generalizability of the findings.

Dr. Malik Y. Kahook, a professor of ophthalmology and chief of the glaucoma service at the University of Colorado School of Medicine in Aurora, was not surprised by these findings.

“It has been known for years that trabeculectomy is an efficient method of lowering IOP, and decreasing the burden of drops can enhance quality of life overall,” he told Reuters Health by email. “After reading this paper surgeons might be more likely to choose surgery first, in the form of trabeculectomy, for appropriate patients with advanced glaucomatous disease.”

“The study’s strengths include the multiple sites and surgeons and the ‘pragmatic’ approach that mimics real-world clinical practices,” added Dr. Kahook, who was not involved in the study. “Weaknesses include the inability to mask patients to the interventions and the fact that a significant number in each group received the alternate-arm treatment during follow-up.”

“Fear of blindness is likely a common reason why patients opt out of eye surgery,” said Dr. Janna Lambson, an optometrist at the University of North Carolina School of Medicine in Chapel Hill.

“This study can be a good way to communicate to patients that surgery is an effective and relatively safe option to manage their advanced glaucoma,” she told Reuters Health by email.

Dr. Lambson, who also was not involved in the study, added, “A weakness is that the study does not mention the exact medications used, so it is unclear if the patients in the topical treatment group were on maximum medical therapy.”

The research team has received funding to follow the participants through five years. “The study’s main weakness is short length of follow-up,” Dr. King explained. “Glaucoma is a lifelong condition that progresses slowly, and longer-term follow-up will provide more evidence of difference in efficacy and safety of interventions.”

SOURCE: The BMJ, online May 12, 2021.

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