Detecting glaucoma progression through optic nerve head hemoglobin concentration using automated colorimetric analysis

Purpose To evaluate whether an algorithm that quantifies changes in hemoglobin (Hb) concentration in the optic nerve head (ONH) can detect progression in glaucomatous eyes with progressive visual field changes. Methods This retrospective cohort study involved eyes with primary open-angle glaucoma (POAG). Eyes were required to have at least five Standard Automated Perimetry (SAP) tests and three ONH photos during follow-up. ONH photos were processed using the Laguna ONhE software (Retinalyze, Spain). The software estimates Hb concentration at the ONH using automated colorimetric analysis. Visual field progression was defined based on the event-based algorithm provided by the guided progression analysis (GPA) software of the Humphrey perimeter. Changes in Hb levels from fundus photos during follow-up were calculated and receiver operating characteristic curve (ROC) regression models were used to assess the performance of Globin Individual Pointer (GIP) changes as an indicator of glaucomatous visual field progression. Results 133 eyes of 102 subjects were included in the study, with 26 (20%) eyes demonstrating progression by the SAP GPA over an average follow-up time of 2.4 ± 1.6 years. The median (IQR) change in SAP mean deviation (MD) between the first and last visits was −2.20 (−4.65 to −0.62) dB in progressing and −0.01 (−1.17 to 1.03) dB in non-progressing eyes ( P = 0.010). Progressing eyes had a median change of −4.9 (IQR: −10.4 to 3.1) GIP units, compared to −1.6 (IQR: −11.2 to 7.8) units for non-progressing eyes ( P = 0.288). A statistically significant negative GIP slope ( P < 0.05) was observed in two (7.7%) of the progressing eyes and 14 (13.1%) of the non-progressing eyes. Each 10-unit decrease in GIP during follow-up was associated with a 22% increase in the odds of progressing by GPA (OR: 1.22; 95% CI: 0.98–1.52; P = 0.071), whereas a 10 unit/year faster slope was associated with 6% higher odds of visual field progression (OR: 1.06; 95% CI: 0.90–1.26; P = 0.456). The area under the ROC curve to detect progression based on GIP change was 0.49 (95% CI: 0.39–0.60). Conclusion Reductions in Hb concentration estimates from fundus photos were not significantly different between progressing and non-progressing eyes. GIP changes overtime were not associated with visual field progression. We believe that the ability to detect glaucoma progression with this method requires improvement.