Retinopathy of Prematurity: Discordance in Disease Expression Among Twin Infants

Background: Retinopathy of prematurity (ROP) is a significant cause of preventable childhood blindness. Twin births offer a unique opportunity to evaluate how individual neonatal factors contribute to ROP development, as co-twins typically share similar prenatal and perinatal environments. Objective: To evaluate how individual neonatal risk factors contribute to ROP severity, differences, and treatment outcomes among preterm twin pairs managed under identical neonatal intensive care conditions. Materials and Methods: This prospective observational study included 24 twin pairs and two singletons born at 27–34 weeks’ gestation (birth weight 850–2650 g) and was screened in accordance with ICROP3 guidelines. Clinical variables, such as gestational age, birth weight, respiratory support, and metabolic stability, were compared within twin pairs. Discordance was defined as any inter-twin difference in ROP stage, severity, or treatment requirement. Treatment options included intravitreal injection, laser photocoagulation, and vitrectomy. Results: Seven twin pairs (2.9 %) demonstrated discordant ROP. In each pair, one twin developed any stage of ROP, including aggressive (treatment-requiring) ROP, while the co-twin exhibited mild or no ROP. Discordant pairs were delivered at 28–31 weeks, with mean birth weights of 1496 ± 523g (affected) and 1322 ± 333g (unaffected). One twin pair had the same ROP stage, but regression occurred at different times. Despite similar durations of oxygen therapy, affected infants experienced more episodes of early respiratory instability and metabolic fluctuations. All affected infants required intravitreal anti-VEGF therapy; one needed supplemental laser for recurrence. Two progressed to stage 4 ROP requiring vitrectomy, with one developing secondary glaucoma. Conclusion: The observed discordance underscores the need for further research with larger sample sizes, inviting the scientific community to contribute to the understanding of ROP variability in twins.