Histopathological characteristics of laser burns produced by a Multicolor Laser Photocoagulator with a Scan Delivery System

1. Takao Hirano¹
2. Kazutaka Hirabayashi¹
3. Yasuhiro Iesato¹
4. Toshinori Murata¹

¹Department of Ophthalmology, Shinshu University School of Medicine, Nagano, Japan

Purpose：To describe the histopathological characteristics of laser burns produced by a novel Multicolor Laser Photocoagulator with a Scan Delivery System (Multi-color pattern scanning laser; NIDEK, Aichi, Japan）that was loaded with yellow (577 nm), red (647 nm) in addition to a conventional green (532 nm) laser.

Methods：Sixteen male mice (12 to 14 weeks) were used in this experiment. Sixty four burns (16 shots using 2x2 pattern) were delivered in each eye using the Multi-color pattern scanning laser. Four eyes with clear media received 64 burns with the green laser. Twelve eyes with an opaque media received 64 burns with the green (4 eyes), yellow (4 eyes) or red (4 eyes), laser respectively. The layers or cells destroyed by the laser were histopathologically evaluated.

Results: Serial sections obtained at every 50 µm from eyes with opaque media, showed 9 (green), 90(yellow), 72(red) effective burns, i.e. destruction limited to the outer retina without retinal or choroidal hemorrhage.

Conclusion：All the three color-lasers of the Multi-color pattern scanning laser successfully delivered effective burns showing minimal but effective destruction to the photoreceptor and retinal pigment epithelial layers. The yellow or red laser was more effective in the eyes with opaque media than the green laser.