578.2nm铜蒸气激光对灰兔眼视网膜损伤阈值的研究

Retinal Injury Thresholds due to Copper Vapor Laser with Wavelength of 578.2 nm

目的确定脉宽20-40ns,脉冲频率为6kHz的578.2nm铜蒸气激光对灰兔眼视网膜的损伤阈值,探讨影响该激光生物学效应的因素。方法以青紫蓝灰兔（15只,30只眼）为实验对象,应用波长578.2nm,脉宽20-40ns的脉冲铜蒸气激光照射兔眼底视乳头下方的后极部,按照进入眼内的激光功率（total intraocular power,TIP）分为6组（15、30、45、60、75和90mW）,照光时间100s,眼底光斑直径2mm。于照光后1h和24h用检眼镜检查视网膜上的曝光点,用眼底照相机和眼底荧光造影检查并记录。计算检眼镜下视网膜损伤阈值（照光后1h和24h）和眼底荧光造影下视网膜损伤阈值（照光后24h）。结果波长578.2nm,频率为6kHz的铜蒸气激光,在眼底光斑直径为2mm,照光时间为100s的灰兔视网膜损伤阈值如下：检眼镜下照光后1h的阈值为TIP=69.24mW,眼底功率密度为1805.97mW/cm^2;检眼镜下照光后24h阈值为TIP=53.25mW,眼底功率密度为1388.92mW/cm^2;眼底荧光造影下照光后24h的阈值为TIP=51.62mW,眼底功率密度为1346.26mW/cm^2。结论在照光时间相同和光斑大小不变的条件下,TIP是影响激光生物学效应的重要因素。在照光后24h内,随着照光后时间延长,损伤逐渐加重。

Objective To determine the lesion thresholds of 578.2 nm laser pulses with pulsewidths of 20-40 ns on the retinas of live rabbit eyes and to inquire into the elements which influence the laser biological effect. Methods Thirty eyes of 15 rabbits were exposed to the laser with wavelengths of 578.2 nm. The exposed animals were divided into six groups[total intraocular power （TIP） = 15,30,45,60,75 and 90 mW]. The duration was 100 s, and the spot size was 2 mm. The au- thors examined and scored all laser impact sites in the retina ophthalmoscopically with fundus photography and fluorescein angiography to identify evidence of visible laser lesion at 1 h and 24 h after exposure. To calculate the retinal injury thresholds, 50% minimum visible lesion probability （ MVLED50 ） and 50% fluorescein angiography visible lesion probabith （ FAVLED50 ）. Results The copper vapor laser with wavelength of 578. 2 nm was irradiated at the condition of exposure time of 100 s and retinal laser spots diameter of 2 mm. The MVLED50 at 1 h was TIP = 69. 24 mW with the power density at the retina = 1 805.97 mW/cm^2 , and the MVLED50 at 24 h was TIP = 53.25 mW, and the power density at the retina = 1 388.92 mW/cm^2 , the FAVLED50 at 24 h was TIP = 51.62 mW,with the power density at the retina = 1 346. 26 mW/cm^2. Conclusions At the same exposure time and the same light spot diameter, TIP is the most important element to determine the laser retinal biology effect. In the 24 hours after exposure, as the time past, the retinal injury is aggravating.