Abstract
Purpose:
Ultraviolet light (UV) can be more hazardous than visible light to the eye. However, the damaging effect(s) of UV on the retina in in vivo has not been fully examined. In this study, we assessed the stimulation-response relationship between the UV exposure dose and the resultant damage in mouse retinas at different UV wavelengths.
Methods:
Under deep anesthesia, the left eyes of 5-week-old ICR albino mice (n=6 for each condition) were exposed to five narrow-band UV lights with 10 nm bandwidth at wavelengths of 330, 340, 360, 380 and 400 nm that generated by using a xenon lamp source with bandpass filters (Asahi Spectra Co., Ltd., Tokyo, Japan). The right eyes, left unexposed to the light, served as controls. For each wavelength, mice were exposed to 3 or 4 different doses (retinal radiant exposure) ranging from 2.5 to 85 J/cm2 to obtain stimulation-response relationship curve. The retinal radiant exposure was determined by multiplying the measured corneal radiant exposure by the intraocular transmittance of the mouse. Fourteen days after the exposure, flash electroretinograms (ERGs) were recorded. Both eyes were enucleated and retinal sections containing the whole retina including the optic disc were stained with hematoxylin-eosin (H & E) and outer nuclear layer (ONL) thickness was measured. The radiant exposure that causes 50 % reduction in ERG a- and b-wave amplitudes, and ONL thickness 250 µm away from optic nerve in superior retina(ED50)was calculated for each wavelength of UV light.
Results:
Compared to unexposed eyes, significant reductions in a- and b-wave ERG amplitudes and in ONL thickness were observed for all wavelengths of UV light tested. ED50 of 330, 340, 360, 380, and 400 nm were calculated to be 7.92, 4.61, 9.41, 12.3 and 91.7 J/cm2 in a-wave, 6.54, 3.52, 7.22, 11.3 and 86.5 J/cm2 in b-wave and 6.1, 6.6, 3.8, 9.6 and 122.9 in ONL thickness, respectively.
Conclusions:
Stimulation-response relationship curves in UV-induced retinal damage were obtained in mice. As expected, retinal damage induced by UV depends on wavelength and radiant exposure. Compared to longer wavelengths, shorter wavelengths cause more severe retinal damage.