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Light and the neonatal eye
1Department of Ophthalmology, University of Birmingham Medical School, UK.
Insights
Premature infants in neonatal units receive significant light exposure, potentially impacting their developing visual systems. Understanding neonatal ocular light dose is crucial for infant eye health.
Area of Science:
- Neonatal photobiology
- Ophthalmology
- Developmental pediatrics
Background:
- Infants born prematurely experience a drastically different light environment compared to the in utero setting.
- Early light exposure may adversely affect the immature visual system of neonates.
Purpose of the Study:
- To quantify the neonatal ocular light dose received by premature infants.
- To assess the impact of lighting conditions in neonatal units on infant visual development.
Main Methods:
- Lighting surveys were conducted in seven neonatal units (NNUs) to measure illuminance and spectral power distribution.
- Datalogging studies quantified light incident on the eyelid and eyelid opening frequency.
- Calculations of retinal irradiance were performed based on measured data and infant age.
Main Results:
- Mean illuminance in NNUs was 470 lux, with intensive care areas being significantly brighter.
- Fluorescent lights in NNUs showed a spectral power distribution weighted towards blue light.
- Eyelid transmission varied by wavelength, acting as a red-pass filter, and eyelid opening decreased with gestational age.
Conclusions:
- Retinal irradiance in premature infants is dependent on postmenstrual age.
- Further research is necessary to determine the precise effects of neonatal light exposure on the developing visual system.
Abstract:
The lighting environment where the baby born prematurely is placed is different from that experienced in utero. As early exposure to light may affect the immature visual system we have attempted to quantify the neonatal ocular light dose. Lighting surveys performed in 7 neonatal units (NNUs) suggested that mean unit illuminance was 470 lux (range 192-890 lux) and intensive care areas within the NNU were significantly brighter than their corresponding low dependency nurseries. The spectral power distribution of fluorescent lights in NNUs was weighted towards the blue end of the spectrum. Datalogging studies demonstrated that between about 30% and 98% of environmental light was incident on the eyelid, which acts as a predominantly red-pass filter, permitting 21% transmission at 700 nm with less than or equal to 5% transmission at 580 nm. Eye-lid opening frequency was quantified: 45% less than or equal to 26 weeks gestational age and decreasing to 7% at 28 weeks gestational age. The onset of the pupillary reflex to light was between 30 and 34 weeks postmenstrual age, the mean diameter was 3.46 mm before this event and 3.02 mm afterwards. Retinal irradiance values calculated from these data show that it is a function of postmenstrual age. Further studies are required to determine its effect on the immature visual system.