810 nm半导体激光致色素兔虹膜组织损伤的研究

Iris induced by 810 nm semi-conductor laser in pigmented rabbits

目的观察810nm半导体激光不同能量参数对色素兔虹膜组织的损伤。方法将12只色素兔按不同激光能量随机分为空白组和100、150、200、250、300mW6组,每组2只兔4只眼,予以810nm半导体激光照射。激光光斑直径1·2mm,曝光时间60s,分别于24h、48h行眼压和眼前段观察,摘除眼球,取虹膜组织行光镜和电镜检查。结果裂隙灯下眼前段变化100、150mW组未见明显反应;200、250、300mW组随照射能量的增加,虹膜皱缩速度加快,激光反应斑时间缩短,颜色加深,直径增大。苏木精-伊红染色100mW组无明显改变;150mW组为可复性损伤改变;200、250、300mW组虹膜血管闭锁,色素颗粒弥散脱失,随能量增加而加重。扫描电镜100mW组无明显改变;150mW组虹膜前表面连接疏松,未见热凝固征象;200、250、300mW组虹膜表面收缩形成凹陷,呈凝固性坏死,并随能量增加而加重。同一能量组激光术后24h、48h行苏木精-伊红染色及扫描电镜比较无明显差别。结论直径为1·2mm的810nm半导体激光光斑照射色素兔虹膜组织60s致虹膜组织损伤的阈值为200mW。

Objective Transpupillary thermotherapy（TTT） with 810 nm semi-conductor laser is used to treat the choroidal neovascularization,but no the report of relevant tissue damage of iris caused by TIT is seen up to now. This study was to observe the intraocular pressure change and histological alteration of anterior segment after photocoagulation of 810 nm semi-conductor laser,and search the optimum power of laser with less damage for iris. Methods The photocoagulation of laser was performed in 12 pigmented rabbits with 810 nm semi-conductor laser,and the duration and beam spot diameter of laser were fixed at 60 seconds and 1.2 mm,respectively. Experimental rabbits were divided into 6 groups according to the different laser power（ control group,100,150,200,250 and 300 mW group） randomly. Two rabbits in each group were sacrificed at 24 and 48 hours after photocoagulation. Light microscopy and scan electron microscopy examination were performed for the histological changes of iris. Results No remarkable change was seen in iris in subthrehold photocoagulation （ 100 - 150 mW group）. With laser power increasing,the formation duration of burn spot was gradually shortened, and the diameter of spot was bigger. Under the light microscopy,cornea and iris tissue were not obviously altered in 100 mW group,and the iris lesions in 150 mW group were reversible. However,in 200 -300 mW group, the swelling and degeneration of cornea and iris was observed in the photocoagulation zone,and the alteration of ocular anterior segment was similar between 24 and 48 hours in every group. Under the electron microscopy, the cornea and iris tissue were not obviously changed in 100 mW group and the heat coagulation sign was not found in 150 mW group. Swelling, degeneration and necrosis of corneal endothelium were seen in 200 -300 mW group. The change of intraoeular pressure was not obvious between 24 and 48 hours in the every group. Conclusion The 810 nm semi-conductor laser can induce iris lesion if the power is over 200 mW ; the optimum duration and beam spot diameter of laser photocoagulation should be fixed at 60 seconds and 1.2 mm respectively.