Mian UK, et al. - In this retrospective cross-sectional study, researchers investigated how sickle cell retinopathy development in adults was influenced by hydroxycarbamide use and fetal haemoglobin (HbF) level. Participants were 300 adult sickle cell subjects examined at the Henkind Eye Institute at Montefiore Medical Center during a 5-year period, from October 2012 to November 2017, for whom data were analyzed to gain information on demography, comorbidities, and ocular and haematology. Among participants, Black and Hispanic subjects with all sickle cell disease (SCD) genotypes, aged 18–71 years, were predominant. Remarkably lower HbF levels were detected in patients with retinopathy vs those without retinopathy, among HbSS patients treated with hydroxycarbamide. Notably, 14·87% was identified as the optimal HbF cut-off point for retinopathy protection, a HbF level of 15% appeared to be the threshold above which the odds for developing retinopathy in SS patients were attenuated by 50%.