Assessing the progression of glaucoma in the central macular region of ganglion cells using optical coherence tomography (OCT)

Abstract

Purpose : To describe an OCT method for identifying glaucoma progression in the local sectors of the thick donut-shaped region of macular ganglion cells.

Methods : The ganglion cell layer (GCL) thickness values for 6 sectors of the donut-shaped macular region (Fig. 1A, inset) were obtained for 84 eyes with at least 4 visits over the span of at least 1 year (mean: 4.2 ± 1.6 yrs). These eyes included 32 healthy control eyes and 52 patient eyes ranging from early glaucoma to advanced glaucoma (24-2 MD: -1.7 to -28.27 dB, mean: -8.72 ± 8.32 dB). To identify progression, linear regression analyses over time were performed for the GCL thickness of each of the 6 donut sectors as well as the global donut thickness. Sectors with regression slopes lower than the 5^th percentile of healthy control slopes were identified for each sector. To visualize larger trends, two sets of linear mixed-effects models were used. Each used the respective eye as a random intercept, while model A used the study group (HC vs glaucoma) as fixed effects and model B used the sector.

Results : The proportion of glaucoma eyes with regression slopes below the threshold for each sector was as follows: 15% (Global), 13% (TS), 13% (S), 12% (NS), 13% (NI), 17% (I), and 15% (TI) (Fig. 1). Comparing the sectors to the global metric in patient eyes, only the inferior (I) sector had more eyes with slopes below threshold compared to global, although a greater proportion of eyes had one or more of the sectors with slopes below the threshold (38.4%). The mixed-effects model A indicated that the patient eyes had rates of change significantly more negative than HC in all sectors except for superior (S) (Table 2 upper rows). For model B, only the TI and I sectors had rates of change significantly more negative than the global metric at 0.61 and 0.56 μm/year faster, respectively (p=0.003, p=0.006) (Table 2 lower rows).

Conclusions : Progression at varying stages of glaucoma can be better identified using sectoral GCL thickness of the macular donut as compared to global GCL thickness. Our analyses suggest that the TI and I sectors progress at faster rates than the global thickness and may be more suitable for detection of progression especially in eyes with early glaucoma.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.