Evaluation of the prevalence of retinopathy of prematurity at Parirenyatwa group of hospitals and Harare central hospital

Abstract

Background: Retinopathy of prematurity is notably one of the causes of avoidable blindness. The risk factors for the development of ROP are very low birth weight(<1500g), low gestational age (GA) (<32 weeks) and duration of oxygen supplementation. The prevalence varies world over, with high income countries having higher figures than their low income counterparts. Zimbabwe is a low income economy, however Harare is urbanised and a significant number of preterm infants at risk of developing ROP do survive. Objectives: 1. To establish the prevalence of ROP at PGH NICU and HCH NNU at 4-6 weeks chronological age. 2. To assess the prevalence of ROP requiring treatment and ROP not requiring treatment a 4-6 weeks chronological age. 3. To establish the risk factors associated with ROP as well as the ocular features of ROP in our neonatal units. 4. To assess the current oxygen delivery protocols for VLBW preterm babies in our neonatal units. Study Design: Hospital based cross sectional analytical study. Methodology: All neonates admitted in the neonatal units were screened weekly to identify patients that met the study inclusion criteria. These infants were enrolled into the study and examined at either the 4th, 5th or 6th week after birth. Ocular examination findings were noted as well as the risk factors for ROP that each neonate may have been exposed to. Details of supplementary oxygen for each neonate were documented, that is duration of oxygen delivery, mode and flow rate. A self-administered questionnaire was completed by medical personnel working in the units, to assess their current knowledge concerning oxygen delivery in VLBW preterm infants. Results: A total of 141 premature babies were enrolled into the study. Twenty infants died and 121 were examined. Six infants were diagnosed with ROP, therefore the prevalence of ROP at 4-6 weeks chronological age was 5.0%. All the infants diagnosed with ROP had spontaneous resolution making the prevalence of children with ROP requiring treatment 0.0%. Three out of 6 (50.0%) had stage 1 disease and 3(50.0%) had stage 2 disease. Location of the disease was as follows; Five out of 6 (83.3%) neonates had disease in zone 3 and 1 (16.7%) had disease in zone 2. The risk factors associated with ROP in this study were, prolonged duration of oxygen supplementation >2 weeks, very low birth weight <1100g and EGA<30 weeks. Seventy per cent of the medical personnel stated that they were aware of an oxygen delivery protocol. However the SaO2 levels that they aim to maintain vary, with most personnel aiming to maintain in the 90-95% and 95-100% ranges. Conclusions: There are VLBW preterm infants who survive and develop ROP in our neonatal units. It follows that the screening of all neonates at risk is essential. Current oxygen delivery protocols must be revisited & revised by medical personnel. Monitoring SaO2 in VLBW preterm neonates would improve with more equipment for monitoring SaO2 as well as more nursing staff.