Semiautomated quantification of β‐zone parapapillary atrophy using blue light fundus autofluorescence

Purpose: To evaluate the reproducibility of measurements of area of β‐zone parapapillary atrophy (β‐PPA) using blue laser fundus autofluorescence (FAF) and confocal scanning laser ophthalmoscopy reflectance (CSLO) measurements and to assess agreement between the two imaging modalities. Methods: Sixty‐five eyes of 45 patients (mean age, 68.2 ± 11.3 years) with established or suspected glaucoma from the Diagnostic Innovations in Glaucoma Study (DIGS) were prospectively included. FAF scans were obtained with the Spectralis HRA+OCT and CSLO reflectance images with the HRTII (both from Heidelberg Engineering, Heidelberg, Germany). Two masked graders independently measured β‐PPA area on 3 consecutive scans using the semi‐automated BluePeak RegionFinder software (BPRF) and on CSLO reflectance images using the optic disc contour line. Reproducibility of β‐PPA area measurements was assessed using intraclass correlation coefficients (ICC). Results: Intragrader reproducibility was 0.997 (95% CI, 0.996–0.998) and 0.995 (95% CI, 0.992–0.996) for grader 1 and 2, respectively, using FAF‐BPRF, and by CSLO, it was 0.991 (95% CI, 0.986–0.994) and 0.988 (95% CI, 0.982–0.992). Intergrader agreement (ICC) was 0.53 (95% CI, 0.331–0.685) for FAF‐BPRF and 0.404 (95% CI, 0.149–0.601) for CSLO (comparison between ICC, p = 0.368). Agreement (ICC) between the two devices was worse for grader 1 (0.356; 95% CI, 0.129–0.549) than grader 2 (0.856; 95% CI, 0.774–0.910) (p < 0.001). Conclusions: Despite excellent intragrader reproducibility for β‐PPA measurements with FAF‐BPRF and CSLO, intergrader reproducibility is low to moderate. Measurements of β‐PPA area obtained with the two instruments are of moderate agreement and, therefore, are not interchangeable.