Incidence and Risk Factors of Retinopathy of Prematurity among Preterm Infants in Shiraz/Iran

Objective: Retinopathy of prematurity (ROP) is a serious complication in preterm infants. To avoid this complication the risk factors leading to the disabling disease should be evaluated and prevented.
Methods: This is a descriptive study. All preterm infants with birth weight under 1500 g and preterm infants with birth weight between 1500-2000 g who had unstable clinical condition and admitted in neonatal intensive care unit from February 2006-March 2007 at tertiary hospitals of Shiraz University, Iran, were introduced into the study. All infants are examined by indirect ophthalmoscopy. Risk factors analysis was performed in two groups. Group 1 consisted of infants with no ROP or ROP that regressed spontaneously, and Group 2 of those with severe ROP that needed laser therapy.
Findings: Of 199 preterms, ROP that needed laser therapy was detected in 19 (9.5%); 65 (32.6%) had ROP that regressed spontaneously and 115(57.8%) had no ROP. Risk factor analysis showed significant P-values for gestational age, birth weight, Apgar score of first minute, mean duration of mechanical ventilation, mean duration of oxygen therapy, eclampsia-preeclampsia, hypoxia, hyperoxia, Pa CO2 >60 mmHg, pH>7.45 and frequent blood transfusions. Using stepwise logistic forward regression showed the three factors mean duration of oxygen therapy, birth weight and mechanical ventilation to be independently significant variables for increasing the rate of ROP.
Conclusion: The main risk factors for development of threshold ROP are low birth weight, mechanical ventilation and duration of oxygen therapy. So it seems that prevention of premature delivery and judicious oxygen therapy is the main step for prophylaxis of ROP.

Keywords
Retinopathy of prematurity; Incidence; Risk factors; Treatment; Hyperoxia