Rapid Initial GCC Thinning Associated with Faster Rates of Central Visual Field Loss

Robert N. Weinreb, MD

More rapid ganglion cell complex (GCC) thinning during an initial follow-up period was associated with faster rates of central visual field (VF) loss over an extended period in patients with glaucoma, according to new findings published in JAMA Ophthalmology.

The cohort study reported a 3.4-fold greater rate of central VF change over the 4.7 years of follow-up for fast macular optical coherence tomography (OCT) progressors, compared with slow macular OCT progressors.

“Given the association of central VF loss with QOL among patients with glaucoma, these results may have clinical importance because early identification of patients at greater risk of subsequent central VF loss can lead to timely treatment, early screening, and better monitoring of patients at risk of fast central VF loss in the future,” wrote Robert N. Weinreb, MD, Chair & Distinguished Professor of Ophthalmology, University of California, San Diego.

Glaucoma is characterized by the loss of retinal ganglion cells (RGCs) and optimal management requires timely detection of glaucomatous damage and monitoring of its progression. Weinreb and colleagues looked to study the association between the rate of GCC thinning and the rate of central VF loss in order to guide treatment intensity for glaucoma.

The retrospective cohort design included patients with primary open-angle glaucoma (POAG) and patients with suspected glaucoma who were enrolled in the Diagnostic Innovations in Glaucoma Study (DIGS) and the African Descent and Glaucoma Evaluation Study (DIGS). All participants were assessed longitudinally with regular follow-up visits with clinical examination, imaging, and functional tests from June 2014 to January 2019.

The study included eyes with a minimum of 3 follow-up macular OCT scans and a maximum of 2 years’ follow-up. Eyes were classified as glaucomatous with at least 2 consecutive abnormal VF test findings with evidence of glaucomatous optic neuropathy.

Investigators assessed central VF loss rates as the change in central VF mean deviation during the 4.7-year follow-up period by univariable and multivariable linear mixed-effects models. Then, based on rates of GCC thinning, eyes were categorized as slow (> –1 μm/y) or fast (≤–1.0 μm/y).

The analysis included a total of 202 eyes of 139 patients, comprising 48 eyes with suspected glaucoma and 154 with POAG. The mean age of participants was 68.7 years and 67 patients were female (48.2%). Of the population, 44 patients (31.7%) were African-American, 13 (9.4%) were Asian, 80 (57.6%) were White, and 2 patients identified as other race and ethnicity (1.4%).

The analysis reported the rate of GCC change was –0.56 μm/y (95% CI, -0.66 to -0.46 μm/y) during a mean initial follow-up of 1.8 years (95% CI, 1.7 – 2.0 years). Data show a total of 163 eyes (80.7%) were classified as slow OCT progressors and 39 (19.3%) were classified as fast OCT progressors.

Those considered fast OCT progressors had a faster mean rate of GCC thinning compared with the slow progressors (– 1.6 μm/y [95% CI, –1.8 to –1.3 μm/y] vs. –0.3 μm/y [95% CI, –0.4 to –0.2 μm/y]; difference, –1.3 μm/y [95% CI, –1.5 to 1.0 μm/y]; P <.001).

The univariable model revealed the rates of 10-2 VF mean deviation worsening among slow and fast OCT progressor groups were –0.10 dB/y (95% CI, –0.16 to 0.00 dB/y) and –0.34 dB/y (95% CI, –0.51 to –0.16 dB/y), respectively, for a difference of -0.26 dB/y (95% CI, –0.45 to –0.07 dB/y; P = .008).

“Our results support the use of macular imaging for monitoring at the time of diagnosis and for monitoring the rate of GCC thinning, which is associated with central VF progression in patients with glaucoma,” Weinreb added.

The study, “Association Between Rate of Ganglion Cell Complex Thinning and Rate of Central VIsual Field Loss,” was published in JAMA Ophthalmology.