To identify risk factors that affect the development of type 2 retinopathy of prematurity (ROP) and progression to type 1 or threshold ROP requiring treatment. Methods

The medical records of premature infants born with a birth weight ≤1,500 g or a gestational age ≤32 weeks were retrospectively reviewed. Potential risk factors were divided into systemic and ophthalmic factors and analyzed by univariate and multivariate logistic regression analyses. Results

Three hundred and twenty-four eyes met the screening criteria. Among them, 41 eyes (12.65%) progressed to type 2 ROP and 21 eyes (6.48%) received treatment after progression to type 1 or threshold ROP. The systemic risk factor associated with progression from type 2 ROP was periventricular leukomalacia and the ophthalmic factor was the existence of nasal ROP at the time of diagnosis of type 2 ROP. Conclusions

Careful examination was needed when type 2 ROP with periventricular leukomalacia or nasal ROP developed because there was a high probability of progression and treatment.