Delayed choroidal perfusion: a fluorescein angiographic finding in retinopathy of prematurity

PURPOSE: Retinopathy of prematurity (ROP) is the leading cause of childhood blindness worldwide. While choroidal involution has been described in animal models, choroidal perfusion in premature infants remains poorly characterized because of limited use of intravenous fluorescein angiography (IVFA). METHODS: This retrospective study systematically analyzed IVFAs performed post-treatment in patients with ROP at the Hospital for Sick Children between 2011 and 2020. Eligible patients had received intravitreal bevacizumab or laser photocoagulation, and only transiting eyes were included to allow complete IVFA phase analysis. Three independent experts graded each IVFA for image quality, presence of delayed choroidal perfusion during the arteriovenous phase, and its location (central, peripheral, or multifocal). Inter-rater reliability was assessed using Fleiss's κ. RESULTS: Of 79 IVFAs reviewed, 74 met quality criteria. The cohort had an average birth weight of 602.6 g and a gestational age of 24.0 weeks. Most (63.5%) had zone I, stage 3+ ROP. IVFAs were conducted at a corrected age of 7.5 months. Delayed choroidal perfusion was found in 64 eyes (86.5%), predominantly multifocal. Only 2 eyes had normal perfusion. Inter-rater agreement was high (κ = 0.85). CONCLUSIONS: Delayed choroidal perfusion is common and persistent in treated ROP patients. To our knowledge, this is the largest IVFA series that systematically describes this underrecognized feature with implications for long-term vision.