AIM: To observe the structural and functional changes of retinal tissue in rats after different duration of intense blue light irradiation.

METHODS: A total of 48 healthy 8-week-old SD male rats were selected and randomly divided into the control group(n=12)and 3, 6 and 12h experimental groups(n=36). The rats in the control group received natural light, and the rats in the experimental groups received blue light with a wavelength of 465±5nm and the illumination of 1000±100lx for 3, 6, and 12h each day. Optical coherence tomography(OCT), fundus fluorescein angiography(FFA)and haematoxylin-eosin(HE)staining of paraffin pathological section were used to observe the changes of the retinal thickness, retinal tissue structure and the function in different directions and layers.

RESULTS: The OCT results showed that the retinal thickness in the superior, inferior, nasal, and temporal sides of rats in different groups was statistically significant(P<0.05), and there was no statistical significant difference between the control group and the 3h experimental group in the total retinal thickness(P>0.05), while the differences between any other two groups were statistically significant(P<0.05); The mean total retinal thickness, internal limiting membrane(ILM)-inner nuclear layer(INL)thickness, outer plexiform layer(OPL)-outer segment(OS)thickness and retinal pigment epithelium(RPE)of rats in each group were statistically significant(P<0.05), and the mean total retinal thickness and OPL-OS thickness were statistically significant between any two groups(P<0.05). The ILM-INL thickness of rats in the control group and 3 and 12h experimental groups was statistically significant(P<0.05), and the thickness of RPE layer in the 12h experimental group was statistically different from that of the 3 and 6h experimental groups(P<0.05). FFA results showed that there was no obvious fluorescence leakage in the fundus of rats in the control group and the 3h experimental group, while there was obvious fluorescence leakage and hyperfluorescence in the retina of the 6 and 12h experimental groups, and the background fluorescence of choroid was enhanced. HE staining showed the atrophy and apoptosis of cells in the optic cell layer, and some lightly stained nucleus. In addition, RPE layer showed atrophy and thinned with the increase of light time, and there was significant difference in the number of the optic cells between the control group and experimental group(P<0.05).

CONCLUSION: The intense blue light irradiation could cause thinning of the retina in rats, with varying degrees of thinning in different layers of the retina. It could also led to decrease and even disappearance of the number of cells in the visual cell layer, the focal atrophy of the RPE layer, and the change of vascular permeability. With the extension of the light time, the structural and functional changes in retinal tissue became more obvious.