Structure–Function Relationships and Glaucoma Detection with Magnification Correction of OCT Angiography

PURPOSE: To investigate the effects of adjusting the ocular magnification during OCT-based angiography imaging on structure–function relationships and glaucoma detection. DESIGN: Cross-sectional study. PARTICIPANTS: A total of 96 healthy control participants and 90 patients with open-angle glaucoma were included. METHODS: One eye of each patient in the control group and the patient group was evaluated. The layers comprising the macula vascular density (VD) and circumpapillary VD were derived from swept-source OCT angiography imaging. The mean sensitivity (MS) of the standard automated perimetry was measured using the Humphrey 24-2 test. Structure–function relationships were evaluated with simple and partial correlation coefficients. A receiver operating characteristic analysis was performed to evaluate the diagnostic accuracy for glaucoma using the area under the receiver operating characteristic curve (AUC). Ocular magnification was adjusted using Littmann’s formula modified by Bennett. MAIN OUTCOME MEASURES: The association between the axial length and VD, structure–function relationships, and glaucoma detection with and without magnification correction. RESULTS: The superficial layer of the macular region was not significantly correlated to the axial length without magnification correction (r = 0.0011; P = 0.99); however, it was negatively correlated to the axial length with magnification correction (r = –0.22; P = 0.028). Regarding the nerve head layer in the circumpapillary region, a negative correlation to the axial length without magnification correction was observed (r = –0.22; P = 0.031); however, this significant correlation disappeared with magnification correction. The superficial layer of the macula and the nerve head layer of the circumpapillary region were significantly correlated to Humphrey 24-2 MS values without magnification correction (r = 0.22 and r = 0.32, respectively); however, these correlations did not improve after magnification correction (r = 0.20 and r = 0.33, respectively). Glaucoma diagnostic accuracy in the superficial layer (AUC, 0.63) and nerve head layer (AUC, 0.70) without magnification correction did not improve after magnification correction (AUC, 0.62 and 0.69, respectively). CONCLUSIONS: Adjustment of the ocular magnification is important for accurate VD measurements; however, it may not significantly impact structure–function relationships and glaucoma detection.