Clinical features and changes of disease spectrum of zone II retinopathy of prematurity: a 10-year review

AIM To report the clinical features and evolution of zone II retinopathy of prematurity (ROP). METHODS RetCam images of preterm infants with zone II ROP at our hospital between January 2009 and January 2019 were reviewed. The location, extent, and severity of ROP were recorded. Eyes were classified as type 1 zone II, type 2 zone II, and mild zone II ROP. The clinical features and evolution of zone II ROP were analyzed. RESULTS In total, 184 infants (302 eyes) were enrolled. Of these, 55 eyes (18%) developed type 1 zone II ROP, 39 eyes (13%) developed type 2 zone II ROP, and 208 eyes (69%) developed mild zone II ROP. The proportion of type 1 zone II ROP significantly decreased over the 10y. The onset of type 2 zone II and mild zone II ROP were 1wk earlier than type 1 zone II, and both regressed at 45wk. Isolated neovascular tuft (popcorn) and double track signs were characteristic manifestations of zone II ROP. Eighty-seven percent of type 1 zone II ROP regressed completely with an unfavorable outcome that emerged in seven eyes after laser treatment. CONCLUSION Zone II is an area with ROP disease at various risk levels. Zone II ROP has unique clinical presentations like popcorn and double track signs. Over time, the proportion of zone II ROP with high risk gradually decrease and respond well to therapy.