PurposeTo evaluate longitudinal quantitative ischaemic and vasculature parameters, including ischaemic index, vessel area, length and geodesic distance in sickle cell retinopathy (SCR) on ultra-widefield fluorescein angiography (UWFA).MethodsOptimal UWFA images from two longitudinal timepoints of 74 eyes from 45 patients with SCR were aligned and a common region of interest was determined. A deep-learning augmented ischaemia and vascular segmentation platform was used for feature extraction. Geodesic distance maps demonstrating the shortest distance within the vascular masks from the centre of the optic disc were created. Ischaemic index, vessel area, vessel length and geodesic distance were measured. Paired t-test and linear mixed effect model analysis were performed.ResultsOverall, 25 (44 eyes) patients with HbSS, 14 (19 eyes) with HbSC, 6 (11 eyes) with HbSthal and other genotypes were included. Mean age was 40.1±11.0 years. Mean time interval between two UWFA studies was 23.0±15.1 months (range: 3–71.3). Mean panretinal ischaemic index increased from 10.0±7.2% to 10.9±7.3% (p<0.005). Mean rate of change in ischaemic index was 0.5±0.7% per year. Mean vessel area (p=0.020) and geodesic distance (p=0.048) decreased significantly. Multivariate analysis demonstrated baseline ischaemic index and Goldberg stage are correlated with progression.ConclusionLongitudinal ischaemic index and retinal vascular parameter measurements demonstrate statistically significant progression in SCR. The clinical significance of these relatively small magnitude changes remains unclear but may provide insights into the progression of retinal ischaemia in SCR.

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Purpose: To describe the association of change in the baseline hemoglobin levels with the development of interferon (INF) retinopathy after the start of pegylated INF (PEG INF) and ribavirin for hepatitis C virus treatment. Methods: This was a retrospective chart review conducted on 12 patients on PEG INF and ribavirin with baseline examination and follow-up during the treatment regimen: 6 developed INF-induced retinopathy and 6 patients were without retinopathy. Serial hemoglobin values for both the groups were recorded at the time of the retinopathy diagnosis in affected patients and the nadir in those without retinopathy. The total percent reduction of hemoglobin was calculated for both the groups. Results: Hemoglobin concentration levels between control and INF retinopathy patients tended to be slightly lower in the group that developed retinopathy. There was no threshold hemoglobin concentration under which the rate of developing retinopathy significantly increased. Greater than 25% drop in hemoglobin conferred a statistically significant risk in the development of INF-associated retinopathy. Conclusion: Patients starting PEG INF and ribavirin require baseline testing and subsequent follow-up based on the rapidity of the decrease in hemoglobin levels to identify the development of retinopathy with treatment.

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