Early light reduction for preventing retinopathy of prematurity in very low birth weight infants

BACKGROUND: Retinopathy of prematurity (ROP) causes vision loss in many premature infants each year, despite the advances being made in treatment. In the search for ways to prevent the disease altogether, the exposure of the retina to bright ambient light following premature birth has been a natural hypothesis, since the premature infant normally would be in the dark in-utero environment. Several controlled studies have now addressed this theory. OBJECTIVES: To answer the question: "Among very low birth weight infants, what is the effect of reducing early environmental light exposure on the incidence of any "Acute ROP", or "Poor ROP Outcomes"? SEARCH STRATEGY: Searches were made of the Cochrane Neonatal Group Register of Controlled Trials, Medline, EMBASE, the Cochrane Library, previous reviews including cross references, abstracts, conference and symposia proceedings, and expert informants. The search terms used were [retrolental fibroplasia or retinopathy of prematurity] and [light or light/ae or lighting or lighting/ae or light/tu or lighting/st]. This search was updated as of November 2000. SELECTION CRITERIA: Randomized or quasi-randomized controlled trials that reduced light exposure to premature infants within the first 7 days following birth were considered for this review. DATA COLLECTION AND ANALYSIS: Data on clinical outcomes including any Acute ROP and Poor ROP Outcome were excerpted by both reviewers independently and consensus reached. Data analysis was conducted according to the standards of the Neonatal Cochrane Review Group. MAIN RESULTS: Data from four recent randomized trials, and one much older quasi-randomized trial failed to show any reduction in Acute ROP, or Poor ROP Outcome with the reduction of ambient light to premature infants' retinas. The number of infants studied to date allows 95% confidence that IF there were a true difference being missed, it would be smaller than 7 percentage points on a background of 54% of all infants under 2 kg developing ROP. REVIEWER'S CONCLUSIONS: Decreasing retinal ambient light exposure in premature infants is very unlikely to reduce the incidence of ROP.