Optimizing visualization in enhanced depth imaging OCT in healthy subjects and patients with retinal pigment epithelial detachment

BACKGROUND This study's objective was to optimize the visualization of three different spectral-domain optical coherence tomography (SD-OCT) display modalities and evaluate enhanced depth imaging (EDI) by comparing the maximum depth of assessment in conventional versus inverted cross-sectional OCT images in healthy subjects and in patients with retinal pigment epithelial detachment (PED). METHODS Cross-sectional SD-OCT conventional and inverted images were obtained with the HRA2 (Heidelberg Retina Angiograph II, Heidelberg Engineering, Heidelberg, Germany). Horizontal as well as vertical sections in three different display modes were blinded for evaluation by three independent, experienced graders for maximal imaging depth of the deep ocular fundus layers. RESULTS The mean imaging depth as measured from the inner segment/outer segment (IS/OS) to the outer choroid of all 14 healthy subjects was 197 ± 44 μm vs 263 ± 56 μm for conventional vs EDI scans: in black/white mode, it was significantly lower (P < 0.001) than in white/black mode (249 ± 42 μm vs 337 ± 71 μm) and color/heat mode (254 ± 48 μm vs 354 ± 73 μm). The mean imaging depth of all 14 study eyes with PED was 240 ± 78 μm vs 345 ± 100 μm for conventional vs EDI scans in black/white mode, and was significantly lower (P < 0.001) than in white/black mode (393 ± 104 μm vs 464 ± 126 μm) and in color/heat mode (373 ± 106 μm vs 453 ± 114 μm). In each display modality of healthy subjects and of patients with PED, EDI scans showed a significantly higher imaging depth than the corresponding conventional scans. CONCLUSION White/black and color/heat modes allow increased imaging depth, compared to black/white mode using both conventional or EDI OCT scans in healthy subjects or patients with PED. EDI obtained with HRA2 significantly improves the imaging depth, compared to conventional OCT scans.