Ganglion Cell Complex Thinning Associated With Faster Central Visual Field Decline

Faster rates of central visual field (VF) decline were found to be associated with rapid thinning of the ganglion cell complex (GCC), according to a study published in JAMA Ophthalmology. Researchers believe that this could support the use of longitudinal macular optical coherence tomography (OCT) scans to assist in clinical decision-making for glaucoma.

Loss of retinal ganglion cells and their axons characterize glaucoma, which leads to changes in the optic disc with VF damage. Optimal management can be achieved through timely detection of glaucomatous damage. Detecting true change over time is difficult as VF testing has high variability. This study aimed to find the association between GCC thinning and the rate of central VF loss.

Patients with primary open-angle glaucoma (POAG) and patients with suspected glaucoma who were enrolled in the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study were included in the current cohort study. All participants were followed-up from June 18, 2014, to January 11, 2019, and data analysis occurred in March 2022. Eyes were included if they had a minimum of 3 follow-up OCT scans and a maximum of 2 years of follow-up.

All participants had an annual comprehensive ophthalmologic evaluation. VF tests taken during follow-up within 6 months of the first OCT visit were included. A minimum of 5 follow-up VFs were required.

Participants needed to be aged 18 years and older, have open angles on gonioscopy, best corrected visual acuity of 20/40 or better, and a refraction within 5.0 diopters spherical and 3.0 diopters cylinder at the time of entry. Participants were excluded if they had a history of trauma or intraocular surgery, coexisting retinal disease, other systemic or ocular diseases that affect VF, substantial cognitive impairment, or an axial length of 27 mm or more.

A total of 202 eyes of 139 participants were included in the study, 48 with suspected glaucoma and 154 with POAG. A total of 51.8% men were included and the mean (SD) age of the participants was 68.7 (10.0) years; 57.6% were White and 31.7% were African American.

The mean GCC thickness at baseline was 90.2 mcm (95% CI, 88.4-92.1) whereas mean baseline of VF mean deviation (MD) was –3.6 dB (95% CI, –4.4 to –2.9). There were 4.7 years (95% CI, 4.5-4.8) of follow-up where a mean of 6.3 VF visits (95% CI, 6.1-6.5) occurred.

The initial follow-up of 1.8 years saw a rate of GCC change of –0.56 mcm/year (95% CI, –0.66 to –0.46) in all eyes. There were 163 eyes that were slow OCT progressors and 39 that were fast OCT progressors. Participants who had fast OCT progress had a faster mean rate of thinning in the GCC compared with the participants with slow progress (–1.6 mcm/year [95% CI, –1.8 to –1.3] vs –0.3 mcm/year [95% CI, –0.4 to –0.2]).

A lower mean intraocular pressure (IOP) was also found in the slow OCT progressor group (14.2 mm Hg; 95% CI, 13.6-14.7) compared with the fast OCT progressor group (15.7 mm Hg; 95% CI, 14.6-16.9) during the follow-up. Faster central visual field mean deviation (10-2 VF MD) worsening was found in the fast OCT progressor group compared with the slow group (β, –0.34 dB/y; 95% CI, –0.51 to –0.16 vs –0.10 dB/y; 95% CI, –0.16 to 0.00). The overall rate of 10-2 VF MD worsening in the univariable model was associated with worse baseline 10-2 VF MD (β, 0.01; 95% CI, 0.00-0.03) and African American race (β, 0.17; 95% CI, –0.01 to 0.33). The multivariable model also found that the fast OCT progressor group had faster rates of 10-2 VF MD worsening.

There were some limitations to this study. All participants were receiving treatment during the study, which means the rate of loss in VF may have been underestimated. Selection bias, ascertainment bias, information bias, and variable follow-up cannot be excluded as possibilities as the data were collected prior to study design. Severity of the disease may have led to intensified treatment and slower rates of VF loss.

The researchers concluded that faster rates of central VF MD worsening was linked to rapid GCC deterioration, which supports the use of macular imaging to monitor the rate of GCC thinning.

Reference

Mahmoudinezhad G, Moghimi S, Nishida T, et al. Association between rate of ganglion cell complex thinning and rate of central visual field loss. JAMA Ophthalmol. Published online November 23, 2022. Doi:10.1001/jamaophthalmol.2022.4973