[Histopathological study on the monkey retina and choroid by diode laser endophotocoagulation].

The fundi of three cynomolgus monkeys were coagulated using a diode laser endophotocoagulator. The histopathological changes of the retina and the choroid were investigated periodically up to 3 months. The damage of the retina extended into the outer plexiform layer following mild burn, into the inner nuclear layer with moderate burn and into the nerve fiber layer on severe burn. The pigment epithelium proliferated with multiple layer cells 1-3 months after the irradiation. The choriocapillaries were obstructed, regardless of the degree of burns, immediately after the irradiation, but recanaliculation was observed at the mild and moderate burns 1-3 months after the irradiation. The effects on the choroid were localized to the inner layer following mild burn, but the damage extended into the outer layer with moderate burns. Following severe burns obstruction of the medium size vessels was observed. The fibrous changes of the choroid increased in accordance with the degree of the burn. The damaged melanophore in the choroid recovered considerably 1 month after the mild burn. On the other hand, many macrophages still remained in moderate and severe burn lesions. These results suggested that diode laser photocoagulation might be effective for the treatment of the choroidal diseases rather than retinal diseases, because diode laser photocoagulation produced the considerable change in the choroid as well as in the retina.