Natural history of retinopathy of prematurity: two-year outcomes of a prospective study.

Purpose: To investigate the 2-year outcomes of the natural history of retinopathy of prematurity (ROP) in Taiwan.

Methods: A prospective study was conducted at two tertiary medical centers. Premature infants were screened and examined for ROP. The postmenstrual ages of developing each stage of ROP and the associated risk factors were recorded.

Results: A total of 698 infants were included. The incidences of ROP and treatment-requiring ROP in all patients with ROP were 29.7% and 37.2%. When only including patients with birth weight of 1,250 g or less, the incidences were 62.2% and 39.1%, respectively. In patients with ROP with birth weight over 1,250 g, 25% of them developed treatment-requiring ROP. The median postmenstrual ages for the development of Stage 1, Stage 2, and Type 1 ROP were 33.0, 34.0, and 34.7 weeks, respectively. Gestational age at birth and birth weight were the most important factors associated with treatment-requiring ROP (hazard ratios of 0.3 and 0.6).

Conclusion: Our hospital-based study reveals an earlier postmenstrual age of developing ROP in this Asian population than in the Early Treatment for ROP study. Infants with birth weight over 1,250 g could still develop treatment-requiring ROP. Suboptimal oxygen control, different genetic dispositions among different races, inconsistencies in ROP diagnosis, and earlier screening might account for such a phenomenon.