OCT Volume Maps Detect Local Progression in Advanced Glaucoma

Abstract

Purpose : To evaluate glaucoma progression detection and monitoring using local indicators of statistical significance on Guided Progression Analysis (GPA, Zeiss, Dublin, CA) change probability maps in patients with advanced glaucoma and a non-significant trend analysis of the circumpapillary retinal nerve fiber layer (cpRNFL).

Methods : Retrospective analysis of a prospective longitudinal study in patients with advanced glaucoma defined as average (cpRNFL) thickness ≤60µm. Subjects with ≥ 4 visits with qualified spectral-domain OCT (Cirrus HD-OCT; Zeiss), ≥ 3 perimetry (Humphrey Field Analyzer; Zeiss), and a minimum follow-up period of 18 months were enrolled. All subjects presented no significant change in trend analysis and no change in the superior and inferior quadrants of the cpRNFL. The GPA for these patients was analyzed, and two groups of subjects were created to be compared: group A with alterations on RNFL thickness map progression on the OCT GPA RNFL/ONH summary, and Group B with no modifications on RNFL thickness map progression on the OCT GPA RNFL/ONH summary. Also, linear regression models were utilized to estimate the MD rate of change per year for each eye. Eyes with p values of the estimated rate of change less than 0.05 were considered as progressors.

Results : We initially screened 782 RNFL and GCIPL OCT GPAs of 281 patients, and 45 eyes were eligible. The full cohort has 43 subjects and 45 eyes. We did a second screen and found that thirty (66.66%) of those 45 eyes exhibited alterations on RNFL thickness map progression on the OCT GPA RNFL/ONH summary while 15 eyes (33.33%) did not. There were 7 out of 30 significant changes in group A and 2 out of 15 in group B with a significance level of 5%. Using the proportional t-test, there is no significant difference in frequency between groups (p =0.69).

Conclusions : We observed a higher percentage of progressors in Group A compared to Group B; however our results did not show statistical significance for the rate of change between groups A and B. Thus, the aspect of the hypothesis that we tested remains unconfirmed. Thus, our findings demonstrate a possible potential utility of evaluating focal regions of interest in GPA change probability maps in eyes with advanced glaucoma patients that have reached the floor effect of the global cpRNFL.

This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.