Nicoline Schalij-Delfos is professor in pediatric ophthalmology at Leiden University Medical Center. She received a PhD degree for her thesis ‘Preterm birth: eyes at risk?! in 1999. The subject of her thesis, retinopathy of prematurity (ROP), is still her main topic in research. Two NEDROP studies, national inventories conducted in 2009 and 2017, provided detailed information about incidence and risk factors for ROP in the Netherlands as well as information about problems encountered in logistics for screening. These studies resulted in several PhD projects and were the basis for national ROP guidelines. Currently her team focusses on the placenta as a predictor for ROP. A collaboration of paediatric ophthalmologists, neonatologists and a fetal pathologist. In her clinical work she is specialized in pediatric lens abnormalities, performing surgery for cataract and lens subluxation. Furthermore, her department is specialized in normal and abnormal visual development, providing a broad spectrum of diagnostic tools, and genetic/systemic diseases causing eye problems in children.