Type I Retinopathy of Prematurity in Infants with Birth Weight Less than 1251 g: Incidence and Risk Factors for its Development in a Nursery in Kuwait

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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 < 0.0001) 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. CONCLUSIONS: 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.