AIM: To observe histopathology changes of spot regional in chinchilla rabbit's retina at different periods after frequency-doubled 532nm laser irradiation.

METHODS: Twenty healthy rabbits were randomly divided into two groups: 16 in group A(laser group)and 4 in group B(normal control group). According to different time after laser photocoagulation rabbits were divided into four subgroups: 1d, 1 week, 2 weeks, 1month, group A with 4 for each subgroup; group B with 1 for each subgroup. To observe the histopathologic changes we used fundus photograph, light microscope, electron microscope and spot diameter calculating in different time points.

RESULTS:(1)Fundus photography: the spot region changed from thick white edema appearance on 1d after the surgery to melanoma attachment by 1 month;(2)Light microscopy: the main damage spot region was concentrated in the outer retina after photocoagulation. Photoreceptor cell appeared necrosis and apoptosis. With the passage of time, glial cells, pigment cells filled injury regional, and fibrous proliferation was formed;(3)Electron microscope: after photocoagulation, structure of membranous disc blurred and arranged in disorder; mitochondrial cristae became vague, fracture or even disappear; obvious vacuolization appeared. It began to appear apoptosis after 1 week, and gradually the fibroblast proliferation appeared;(4)Spot size: the spot size was the maximum at 1d, then gradually became smaller, spot size down to 85% at one-week time, 80% at 2-week time, and 79% at one-month time.

CONCLUSION: Frequency-doubled 532nm laser irradiation of pigmented macular, spot reaction is most obvious at 1d and stabilized at about 2 weeks.