Risk Factors Evaluation of Threshold Retinopathy of Prematurity

Purpose: This study aimed to evaluate risk factors associated with threshold retinopathy of prematurity (ROP) in premature infants referred to Farabi Eye Hospital during 2008-2009. Since blindness and sever visual impairments will occur in a high percentage of infants stricken with threshold retinopathy, we intended to examine relationship between demographic factors and threshold retinopathy in Farabi Eye Hospital, which, as a tertiary center, represents an appropriate sample of Iran’s population. Methods: In this retrospective case-control study, infants less than 37 weeks and/or birth weight less than 2,500 grams referred to Farabi Eye Hospital were included. The eyes were examined and a questionnaire was filled out for each infant. Based on the recording data, the relation between risk factors and threshold ROP was assessed. Results: Out of 1,718 eyes participated in this study, 791 eyes had retinopathy. The incidence of threshold retinopathy in this study was 7.4 percent. We could figure out significant relationships between gestational age, birth weight, oxygen supplementation, duration of ventilation, blood transfusion, respiratory distress syndrome (RDS), postconceptual age and chronic respiratory disease with threshold ROP using independent sample t-test between two groups (infants with threshold retinopathy and infants without it). Cross-tab test revealed a significant relation between threshold retinopathy and risk factors such as sepsis (p=0.006), oxygen supplementation (p=0.000), blood transfusion (p=0.004), RDS (p=0.000), weight (p=0.000) age at first examination (p=0.000), and duration of ventilation. Logistic regression showed that the age (postmenstrual) more than 40 weeks at the time of first examination could be the predicting factors of threshold retinopathy. Conclusion: The most important risk factors of threshold ROP are low gestational age, low birth weight, delayed in initial examination and the duration of oxygen therapy.