Behavior of SD-OCT-detected hyperreflective foci in the retina of anti-VEGF-treated patients with diabetic macular edema

Abstract

Purpose: Hyperreflective foci (HFs) are observable within the neurosensory retina in diabetic macular edema (DME) using spectral domain optical coherence tomography (SD-OCT). HFs have also been seen in wet age-related macular degeneration (AMD), although the origin is still unknown; however, they reduced significantly during anti-VEGF (vascular endothelial growth factor) therapy, and their baseline amount seemed to correlate with treatment success. In this study the behavior of HFs was evaluated during anti-VEGF therapy for DME.

Methods: Fifty-one patients (mean age: 67 years) underwent SD-OCT before and one month after one anti-VEGF injection (ranibizumab: n = 30; bevacizumab: n = 21). The HFs were semiquantitatively counted, assigned to three groups (group A: HFs n = 1-10; group B: n = 11-20; group C: n > 20), and correlated to the course of visual acuity and foveal thickness (paired t-test). Additionally the baseline HbA1c was categorized and correlated to baseline HFs (Spearman Rho).

Results: In all eyes, HFs of various amounts were detected in the foveal and parafoveal area. The mean number of HFs reduced significantly from 16.02 to 14.32 in all patients (P = 0.000), whereas foveal thickness reduced from 445.5 to 373.9 μm (P = 0.000) and visual acuity increased from 62.0 to 66.0 ETDRS letters (P = 0.003). Regarding the three HF groups, a reduction of the level stages was observed in 43.1% (stable: 54.9%; more: 2.0%). This reflects a HF distribution change from 31.4% to 62.7% (group A), from 45.1% to 31.4% (group B), and from 23.5% to 5.9% (group C). The HbA1c correlated significantly to the overall HF amount at baseline (0.880; P = 0.000); however, no distinct overall correlation was found between the HF reduction and the course of visual acuity or retinal thickness. Only in cases of complete edema resolution (25%) did HFs reduce significantly (P = 0.008).

Conclusions: As in wet AMD, HFs are frequently found in DME and behave similarly under anti-VEGF therapy. Thus, a HF reduction was observable mainly in cases of complete edema resolution; however, no distinct correlation with visual acuity was noticed, presumably mainly due to the enhanced inhomogeneity in the disease progress of DME. Interestingly, the baseline HF amount seems to correlate positively with HbA1c values indicating the severity of disease.