Hyperreflective retinal spots in normal and diabetic eyes : B-Scan and En Face Spectral Domain Optical Coherence Tomography Evaluation

Purpose: To evaluate hyperreflective retinal spots (HRS), in normal subjects and diabetic patients without and with macular edema (diabetic macular edema, DME), on linear B-scans and corresponding en face image of spectral-domain optical coherence tomography. Methods: Retrospective evaluation of images of 54 eyes/subjects (16 normal subjects, 19 diabetic patients without DME, and 19 with DME). On horizontal B-scan spectral-domain optical coherence tomography, passing through the center of the fovea, the following characteristics of HRS were evaluated: location (inner retina or outer retina), size (<= 30 or >30 mu m), reflectivity (similar to nerve fiber layer or to retinal pigment epithelium-Bruch complex), and presence or absence of back shadowing. On en face spectral-domain optical coherence tomography, the following patterns were evaluated: 1) isolated HRS (not corresponding to any visible lesion); 2) HRS corresponding to a segment of retinal capillary or microaneurysm wall; and 3) HRS corresponding to hard exudate. All gradings were performed twice by two graders in a masked fashion. Results: Size <= 30 mu m, reflectivity similar to nerve fiber layer, and absence of back shadowing were associated with absence of vessels or any other lesion on en face image (P = 0.0001 for all). Size <= 30 mu m, reflectivity similar to retinal pigment epithelium-Bruch complex, presence of back shadowing, and location in the outer retina were all associated with presence of hard exudate on en face imaging (P < 0.0001 for all). Multiple logistic regression analysis showed that HRS present in the inner retina (P < 0.0001), size >30 mu m (P = 0.0029), and presence of back shadowing (P < 0.0001) are directly associated with presence of microaneurysms on en face image. Intragrader and intergrader repeatability were excellent for all evaluations. Conclusion: Hyperreflective retinal spots <= 30 mu m, reflectivity similar to nerve fiber layer, and absence of back shadowing may represent activated microglial cells; HRS >30 mu m, reflectivity similar to retinal pigment epithelium-Bruch complex, presence of back shadowing, and location in the outer retina may represent hard exudate; HRS >30 mu m, presence of back shadowing, and location in the inner retina may represent microaneurysms. These hypotheses may be tested in further studies.