Niziol LM, et al. - Experts evaluated the time between initial glaucoma treatment of the study eye (SE) and the need for treatment of the fellow eye (FE). They also ascertained the concordance between rates of progression in SEs and FEs. Almost half among patients with newly diagnosed open-angle glaucoma had initial treatment of both eyes. After 7 years, bilateral treatment was carried out in approximately two-thirds of patients. Out of the variables predictive of FE treatment, hypertension and intraocular pressure (IOP) were included in the modifiable factors. Findings suggested similar slopes of mean deviation (MD) between SEs and treated FEs. Therefore, SE change was seen to be a harbinger of FE change and needs close surveillance.

Methods

• In this post hoc analysis of participants from the Collaborative Initial Glaucoma Treatment Study, researchers followed up 607 participants with newly diagnosed open-angle glaucoma in 1 or both eyes for up to 11 years.
• They designated an SE at baseline and randomized to medical or surgical treatment.
• By protocol, they treated FEs when eligible or at physician discretion.
• In order to estimate the probability of FE treatment over time and to test baseline and time-dependent predictors of treatment, survival analysis methods were used.
• They calculated the disease trajectory with linear regression as the patient eye–specific slopes of mean deviation (MD) and intraocular pressure (IOP) over time, and correlations between SE and FE trajectories were calculated,.
• They calculated the data from October 1993 to December 2004 and analyzed from September 2012 to May 2018.
• Main outcomes and measures included the time to FE treatment and slopes over time of MD and IOP in SEs and FEs.

Results

• As per data, out of the 607 included patients, 334 (55.0%) were male and 337 (55.5%) were white, and the mean (SD) age was 58.0 (10.9) years.
• They treated a total of 291 FEs (47.9%) at baseline, 123 (20.3%) were eventually treated, and 193 (31.8%) never received treatment.
• Results demonstrated that the probability of FE treatment for open-angle glaucoma was 0.57 at 1 year and 0.68 at 7 years after randomization.
• Findings suggested a significant association of the characteristics with an increased hazard of FE treatment included older age (hazard ratio [HR], 1.33; 95% CI, 1.08-1.64; P=.007), hypertension (HR, 1.76; 95% CI, 1.16-2.67;P=.008), higher IOP (HR, 1.24; 95% CI, 1.20-1.29;P < .001), large cup-disc ratio (HR, 1.40; 95% CI, 1.23-1.58;P < .001), and worse MD.
• Between SEs and FEs, correlations in MD slopes initially, eventually, and never treated were 0.73, 0.71, and 0.34, respectively.
• In IOP slopes, comparable correlations were 0.57, 0.24, and 0, respectively.