Diabetic Macular Ischemia Diagnosis: Comparison between Optical Coherence Tomography Angiography and Fluorescein Angiography

Purpose. To compare fluorescein angiography (FA) and optical coherence tomography angiography (OCTA) images of foveal avascular zone (FAZ) in patients with diabetic retinopathy (DR) with and without diabetic macular ischemia (DMI). Methods. The Wilcoxon signed-rank test was used to compare area measurements and p values of <0.05 were considered statistically significant. FA and OCTA images were independently graded by 2 observers that reached agreement regarding quantitative DMI according established protocols. The ischemic area was divided into "large" macular ischemia (superior to 0.32 mm2) and "small" (inferior to 0.32 mm2) groups. Quantitative analyses of the FAZ were performed using custom software. Results. Thirty-four eyes from 34 diabetic patients were enrolled. Subjects with DMI presented a mean area on FA and OCTA of 0.68 ± 0.53 mm2 and 0.58 ± 0.35 mm2, respectively (p = 0.1374). Patients without DMI presented a mean area on FA and OCTA of 0.19 ± 0.67 mm2 and 0.20 ± 0.79 mm2, respectively (p = 0.9594). The ICC for the FAZ measurements between the 2 observers on FA and OCTA was 0.96 and 0.92, respectively. Conclusion. OCTA represents a novel technique for the diagnosis of DMI and it may become an alternative to FA for this purpose.