阈下能量经瞳孔热疗对正常大鼠视网膜的影响

目的 研究正常棕色挪威大鼠(BN大鼠)视网膜在810 nm激光阈下能量经瞳孔热疗(TTT)后的改变。方法 雄性BN大鼠36只，使用810 nm激光，采用不同阈下能量对BN大鼠进行TTT。分别于TTT后第1、3、7、14 d进行彩色眼底照相和眼底荧光造影(FFA)。TTT后6、12h，1、3、7、14d各处死6只大鼠，进行组织病理学观察。6、12h和1 d的组织用TdT介导dUTP缺口末端标记法(TUNEL)检查细胞凋亡。结果 TTT后第1 d可见大部分光斑处视网膜灰白色水肿。第3 d视网膜水肿减轻，RPE脱色素。其后视网膜逐渐出现色素沉着。FFA中可见到不同程度的高荧光。组织病理学切片上可见所有在眼底照相上曾出现灰白水肿的病灶，视网膜结构均有显著破坏。TUNEL染色可见视网膜全层均有细胞凋亡。TTT能量最低组6 h时凋亡细胞最多；激光斑旁视网膜较激光斑中央视网膜凋亡细胞多。结论 TTT阈下能量可引起不可逆的视网膜损伤，即使无病理改变也能引起视网膜细胞的凋亡。

Influence of subthreshould transpupillary thermotherapy on rat retina

Objective To investigate the effect of irradiance of various powers of subthreshould transpupillary thermotherapy (TTT) on retina in Brown Norway rats (BN Rats). Methods Thirty-six male BN rats received irradiance of different powers of subthreshould TTT with a 810 nm wave-length through a contact lens. Fundus color photography and fundus fluorescence angiography(FFA) were performed on day 1,3,7 and 14 after TTT. Six rats were sacrificed at 6 hour, 12 hour,1 ,3 , 7,and 14 days separately for histological study. Cells apoptosis was tested by TdT mediated dUTP nick end labelling (TUNEL). Results Retinal whitening and edema could be found at majority of the laser spots on day 1 and was attenuated on day 3. Retinal pigmentation with hyperfluorescence gradually occurred after TTT. Obvious retinal structure disorder at the edema area could be seen from histological sections. Cell apoptosis was demonstrated in all layers of retina and reached its highest amount 6 hours after TTT in the lowest power group. There were more apoptosis cells in retina near the laser spots rather than inside the laser spots. Conclusion Subthreshould TTT may cause irreversible retina destruction, and it may lead to cell apoptosis of retina even without obvious histological change.