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목적 : Subvisible selective retina therapy (SRT) was designed to target retinal pigment epithelium (RPE) without damaging adjacent photoreceptors. Recently, SRT have been considered as an alternative laser therapy of conventional photocoagulation(PC) in treatment of diabetic macular edema or central serous chorioretinopathy. This study evaluated the changes in retinal oxygen saturation and retina histology after SRT compared to PC in rabbits.
방법 : One eye in each of 10 chinchilla bastard rabbits was treated with 144 spots of SRT (527 nm, 20–25 µJ, 200 µm) or conventional laser treatment (577 nm, 150 mW, 200 µm), respectively. After treatment, fundus photography, optical coherence tomography, and fluorescein angiography were performed to detect lesions. At 1 week post-treatment, oxylab was used to determine retinal oxygen saturation in untreated, SRT-treated, and PC-treated areas in five eyes. Histologic evaluation was performed using light and electronic microscopy. At 4 weeks post-treatment, the same procedures were performed.
결과 : At 1 week post-treatment, mean retinal oxygen saturation in the PC-treated area (23.3 ± 7.2 mm Hg) was relatively higher than in the untreated (16.6 ± 4.3 mm Hg) and SRT (15.34 ± 5.3 mm Hg) areas. Similar results were found at 4 weeks post-treatment (PC-treated, 25.3 ± 8.5 mm Hg; untreated, 14.4 ± 5.2 mm Hg, SRT-treated, 15.2 ± 4.6 mm Hg). OCT and histological examinations revealed selective RPE damage while sparing photoreceptors in the SRT lesion. In contrast, broad damage in multiple retinal layers including the photoreceptors was observed in conventional PC lesions
결론 : Increased retinal oxygen saturation after conventional PC might be due to widespread destruction of retinal layers including photoreceptors which is most oxygen consuming structure in retina. In contrast, relatively unchanged retinal oxygen saturation was observed in SRT lesions with intact retinal layers and photoreceptors. SRT can be used as an photoreceptor saving laser therapy in RPE dysfunction diseases such as DME or CSC
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