RESUMEN
To report the rate of acute retinopathy of prematurity [ROP] and Type I ROP among infants with birth weight [BW] <1251 g and identify the risk factors for the development of Type I ROP. A retrospective review of ROP records of infants with BW <1251 g was performed to identify infants with acute ROP and Type I ROP. Infants with Type I ROP were compared with those without Type I ROP to assess the risk factors for the development of Type I ROP. P < 0.05 was statistically significant. Multivariate analysis was performed and odds ratio [OR] and 95% confidence intervals [CI] were calculated. Among the 207 infants with BW <1251 g, acute ROP occurred in 154 infants [74.4%] and Type I ROP in 95 eyes of 50 infants [24.4%]. The numbers of infants with BW <750 g and BW <1000 g were 19.3% and 58.4%, respectively, and the incidences of Type I ROP were 50% and 36.4%, respectively, among them. Forty-four [46.3%] eyes were treated at stage 2+ ROP in zone I or II. All the eyes treated for Type I ROP showed complete regression. Gestational age at birth [OR 0.657, 95% CI: 0.521-0.827; P< 0.000l] and number of ventilated days [OR 1.017, 95% CI: 1.005-1.029; P= 0.006] were identified as independent risk factors for the development of Type I ROP. The rate of Type I ROP in this study is higher than that in previous studies due to the higher number of infants with BW <1000 g in our cohort and the treatment of more eyes with stage 2+ ROP. However, all the treated eyes had a favorable outcome. Gestational age at birth and number of ventilated days were independent risk factors for the development of Type I ROP