[Retinal light damage: I. The influences of light intensity and exposure duration at moderate and low intensities of cyclic light].

PURPOSE: To study the influences of moderate- and low intensity of cyclic light exposure on the light damage of rat retina and its relationship with light intensity and exposure duration.

METHODS

Twenty five 8-10 weeks old of female Sprague-Dawley rats were divided into 5 groups randomly. One group were as controls reared in dark-room, others were exposured to 12 hour light: 12 hour dark cyclic white xenon light from 3 to 28 days. The light intensities were 90-115 Lux(100 Lux), 400-650 Lux(500 Lux), 800-1,150 Lux(1,000 Lux), 1,400-1,650 Lux(1,500 Lux) separately. After various duration of exposure, the retina were evaluated with light microscopy, electron microscopy and morphometric study.

RESULTS

Except for the intensity of 100Lux group, all of the other exposure intensities can induce the light damage of rat retina. The photoreceptor cells were affected most early. The higher of light intensity and the longer of exposure duration, the severer of the photoreceptor cell loss. In the severely damaged eye, RPE were also damaged.

CONCLUSIONS

For the light damage of rat retina which is induced by moderate- or low intensity of cyclic light, the damage degree was both affected by light intensity and exposure duration.