Association of Rates of Ganglion Cell and Inner Plexiform Thinning With Development of Glaucoma in Eyes With Suspected Glaucoma

Importance In eyes with suspected glaucoma, it is clinically relevant to find diagnostic tests for the risk of development of perimetric glaucoma. Objective To investigate the association between rates of ganglion cell/inner plexiform layer (GCIPL) and circumpapillary retinal nerve fiber layer (cpRNFL) thinning and the development of perimetric glaucoma in eyes with suspected glaucoma. Design, Setting, and Participants This observational cohort study used data collected in December 2021 from a tertiary center study and a multicenter study. Participants with suspected glaucoma were followed up for 3.1 years. The study was designed in December 2021 and finalized in August 2022. Exposures Development of perimetric glaucoma was defined as having 3 consecutive results showing abnormal visual fields. Using linear mixed-effect models, rates of GCIPL were compared between eyes with suspected glaucoma that did and did not develop perimetric glaucoma. A joint longitudinal multivariable survival model was used to investigate the performance of rates of GCIPL and cpRNFL thinning in predicting the risk of developing perimetric glaucoma. Main Outcomes and Measures Rates of GCIPL thinning and hazard ratio (HR) of developing perimetric glaucoma. Results Among a total of 462 participants, the mean (SD) age was 63.3 (11.1) years, and 275 patients (60%) were female. Of 658 eyes, 153 eyes (23%) developed perimetric glaucoma. The mean rates of GCIPL thinning were faster in eyes that developed perimetric glaucoma (−1.28 vs −0.66 μm/y for minimum GCIPL thinning; difference, −0.62; 95% CI, −1.07 to −0.16; P = .02). Based on the joint longitudinal survival model, every 1-μm/y faster rate of minimum GCIPL and rate of global cpRNFL thinning were associated with a 2.4 and 1.9 higher risk of developing perimetric glaucoma, respectively (HR, 2.4; 95% CI, 1.8 to 3.2, and HR, 1.99; 95% CI, 1.76 to 2.22, respectively; P < .001). Among the predictive factors, African American race (HR, 1.56; 95% CI, 1.05 to 2.34; P = .02), male sex (HR, 1.47; 95% CI, 1.02 to 2.15; P = .03), 1-dB higher baseline visual field pattern standard deviation (HR, 1.73; 95% CI, 1.56 to 1.91; P < .001), and 1-mm Hg higher mean intraocular pressure during follow-up (HR, 1.11; 95% CI, 1.05 to 1.17; P < .001) were associated with higher risk of developing perimetric glaucoma. Conclusions and Relevance This study found that faster rates of GCIPL and cpRNFL thinning were associated with higher risks of developing perimetric glaucoma. Rates of cpRNFL thinning and specifically GCIPL thinning may be useful measures for monitoring eyes with suspected glaucoma.