Light and the developing retina

Abstract

Retinopathy of prematurity (ROP) has increased in the United States in the past decade. Its resurgence has been attributed to advances in medical care which have increased the survival of infants less than 1000 g. Retinal immaturity and exposure to supplementary oxygen are generally accepted as the principal factors associated with ROP, however precocious exposure of the immature retina to light may also contribute. The preterm infant is routinely exposed for the duration of hospital stay to bright continuous light at levels which produce retinal damage in animals. A recent study has provided evidence implicating light in ROP. Preterm infants for whom the light levels were reduced had a lower incidence of ROP, compared to a similar group of preterms exposed to standard levels of nursery light. Given the problems of a non-randomized design, the results must be considered preliminary; however the findings are substantiated by parallel results in both hospitals studied and by an effect of exposure to light within the treatment group. Speculations regarding the mechanisms of light as a contributor to ROP include: alterations of retinal metabolism, cellular damage by phototoxicity, and the generation of free radicals. Mechanisms of phototoxicity are compatible with theories of oxygen toxicity. Light may not be necessary for ROP to occur, but it may increase the risk.

Pre‐term delivery and subsequent ocular development

“…They stressed two conditions where obviously the pre-term and the full-term infant differ: a) the access of light to the pre-term retina, and b) a lower temperature of the anterior eye segment than encountered in utero. As the most obvious of the two, untimely photostress might be of importance not only as a co-factor in ROP (Glass 1990), but also for retinal development in general.…”

Safety of neonatal phototherapy lamp exposure

“…There may, however, be factors of increased light sensitivity for the maturating retina of the neonate. This coincides with associations of light exposure of the neonate and subsequent development of retinopathy of prematurity (ROP) [16,17]. In addition, references have also been made relating to effects such as the generation of reactive oxygen species by visible light in skin and where Liebel et al [18] demonstrate this effect using live skin cell cultures.…”

Ambient light, ophthalmic artery blood flow velocities and retinopathy of prematurity

“…The results indicate that the immature retina may have poor antioxidant defences and that hyperoxia could result in damage to the developing retinal structures, including the mesenchymal stroma which gives rise to the retinal vascular system (14,15). An additional exposure to light could contribute to the occurrence of retinopathy through phototoxicity or through the generation of oxygen free radicals (9, 16,17). Non-invasive quantitative determinations of the circulation of the eye have been limited to animal experiments.…”