Rate of Visual Field Change in Glaucoma Treatment Similar to Healthy Individuals Over 25 Years

Balwantray C. Chauhan, PhD

The rate of visual field change in patients receiving treatment for glaucoma was similar to the rates in healthy individuals over a median follow-up of more than 25 years, according to a recent cohort study.

Data show 31 patients (78%) with glaucoma had rates of mean sensitivity change within the range of healthy participants (between -0.20 dB/y and 0.15 dB/y).

“Although some selection biases may have underestimated the extent of visual field change, the findings of this study are relevant to a large portion of the population with glaucoma and highlight the fact that most patients who receive treatment for glaucoma have rates of visual field that are modest and within the range of healthy individuals,” wrote study author Balwantray C. Chauhan, PhD, Department of Ophthalmology and Visual Sciences, Dalhousie University.

An accurate estimation of the rate of visual field change may be important, as the same rate has different consequences depending on age, life expectancy, and severity of visual field damage at diagnosis.

The current longitudinal prospective cohort study was conducted in a hospital-based setting from January 1991 - February 2020. Patients with glaucoma and healthy participants were selected from a longitudinal prospective study initiated in 1991 that examined the value of new perimetric techniques for detecting the earliest progression of open-angle glaucoma.

Inclusion criteria for patients with glaucoma consisted of a clinical diagnosis, visual field mean deviation between - 10 dB and -2 dB using standard automated perimetry, and open iridocorneal angle based on gonioscopic examination. Healthy individuals were included if they had a normal ocular examination, intraocular pressure (IOP) ≤22 mm Hg, no family history of glaucoma, and no history of undergoing an ocular surgical procedure.

Study participants underwent testing with standard automated perimetry every 6 months using the appropriate near correction for testing distance. The individual rate of mean sensitivity change was computed through ordinary least-squares regression analysis.

Linear mixed-effects modeling estimated the mean rate of mean sensitivity change in each group and the impact of baseline mean sensitivity, baseline age, and follow-up intraocular pressure for rate estimates.

The study population consisted of 40 patients with glaucoma (median age, 53.07 years; 21 men, [52%]) and 29 healthy participants (median age, 48.80 years; 17 women [59%]). Most patients (n = 65 [94%]) self-identified as White, with the exception of 2 patients with glaucoma (1 self-identified as Black and 1 self-identified as South Asian) and 2 healthy participants who both self-identified as South Asian.

The median follow-up among patients with glaucoma was longer compared to healthy participants (25.65 years versus 19.56 years, respectively). Moreover, the mean follow-up IOP was observed to be similar between groups, with a median of 15.83 mm Hg among patients with glaucoma versus 14.94 mm Hg among healthy participants.

The linear mixed-effects modeling showed that the mean rate of mean sensitivity change among healthy participants was 0.003 dB/y (95% CI, -0.062 to 0.068; P = .93). After adjustments, the mean rate of mean sensitivity change was -0.032 dB/y faster among patients with glaucoma, but the difference was not statistically significant (95% CI, -0.134 to 0.070; P = .53).

Investigators noted that among covariates, only baseline mean sensitivity was associated with the rate of mean sensitivity change (mean, 0.021 dB/y/dB; 95% CI, 0.002 - 0.041; P = .03).

The study, “Rates of Visual Field Change in Patients With Glaucoma and Healthy Individuals: Findings From a Median 25-Year Follow-up,” was published in JAMA Ophthalmology.