Optical coherence tomography (OCT) and OCT Angiography in Stages 3 and 4 proliferative sickle cell retinopathy

Abstract

To investigate macular findings in Goldberg stages 3 and 4 proliferative sickle cell retinopathy (PSCR) using optical coherence tomography (OCT) and OCT Angiography. A case-control study using retrospective OCT and OCTA data from PSCR eyes (cases) and prospective data from age and sex-matched normal (controls). OCTA data included vessel density (VD) in the superficial capillary vascular plexus (SCP) and deep capillary vascular plexus (DCP), foveal avascular zone (FAZ) characterization, including the shape (in the SCP & DCP), size (area covered), and perimeter. OCT data were whole, superior, and inferior hemi-retina thickness for the superficial and deep retina. There were 38 OCT / OCTA scans of PSCR eyes of 21 SCD patients; ten eyes were excluded for not meeting inclusion criteria. We analyzed nineteen (19) patients (ten unilateral and 9 bilateral), 28 eyes, nine SS eyes (32%), and nineteen SC eyes (68%). The controls consisted of 29 eyes of 16 normal subjects (three unilateral and 13 bilateral). The commonest FAZ shape in PSCR was “irregular” in 14 eyes (50%), followed by “round” in 11 eyes (39.3%) versus controls, the commonest shape “round” in 18 eyes (62%), followed by “irregular” 9 eyes (31%) (p = 0.165). FAZ area and perimeter were larger in PSCR (p > 0.05). The deep and superficial VD was reduced in PSCR. The mean whole deep VD for cases was 48.9 ± 6.1 versus 52.9 ± 6.4 for controls (p = 0.019). Mean whole superficial VD for cases was 47.4 ± 5.5 versus 49.8 ± 3.4 for controls (p = 0.058). Retina thickness in the whole, superior and inferior hemi-retina, for superficial and deep retina, was higher in PSCR compared to controls (p < 0.05). Superficial whole thickness for cases and controls were 287.0 μm [IQR 35.3 μm] versus 273.0 μm [IQR 18 μm] respectively (p = 0.008). Deep whole thickness for cases and controls was 287.0 μm [IQR 35.25 μm] versus 273.0 μm [IQR 18 μm] (p = 0.008). VD was reduced in SS compared to SC eyes (deep whole VD: 50.28 ± 6.01 vs 46.78 ± 5.80) (p = 0.139). Retina thickness in SS was reduced relative to SC. Peripheral retinal laser photocoagulation did not affect VD, though it was associated with a thinner macula. OCT/OCTA of stage 3 and 4 PSCR revealed reduced VD in the DCP and SCP. Despite the thin temporal retina in SCD, there is a thicker whole, superior, and inferior hemiretina in both the superficial and deep retina. An irregularly shaped FAZ is common, a reflection of abnormal microcapillary loss in the perifoveal area.