Risk factors associated with retinopathy of prematurity in preterm infants treated at a tertiary level hospital

Background. Retinopathy of prematurity (ROP) is defined as a peripheral proliferative vitreoretinopathy in which immaturity (determined by gestational age and birth weight) and oxygen are more decisive factors. We undertook this study to analyze the relative risk for development of ROP in relation to gestational age and birth weight in infants. Methods. We carried out a retrospective, analytical, cross-sectional, single center trial in preterm infants with a gestational age < 37 weeks and a birth weight < 2,000 g. We performed fundus examination with binocular indirect ophthalmoscopy at different times according to gestational age. Injuries are accounted for using the international classification. Results. We included two groups: I) healthy individuals and II) those with retinopathy of prematurity. Group I included 217 healthy subjects, 91 females and 126 males, with a mean gestational age of 30.95 +/- 2.7 weeks and a weight of 1291.98 +/- 255.93 g (range: 620-2035). Group II was comprised of 127 patients, 65 females and 62 males with a mean gestational age of 29.37 +/- 1.77 weeks (range: 26-34) and a weight of 1089.31 +/- 194.74 g (range: 630-1650). Stage 1 retinopathy predominated (70.1%), followed by stage 2 (21.3%) and stage 3 (7.1%); 9.4% presented a type 1 prethreshold retinopathy and 4.7% threshold. The group of 28-29 weeks showed a factor of 2.37 times more risk of developing ROP and was the group with the highest incidence with 64.13% at 30-31 weeks after which the risk begins to decrease. Conclusions. Preterm infants with gestational age between 28 and 29 weeks are at increased risk for developing ROP.