Chew P T, Wong J S, Chee C K, Tock E P
Department of Ophthalmology, National University of Singapore, Singapore.
Clin Exp Ophthalmol. 2000 Feb;28(1):53-7. doi: 10.1046/j.1442-9071.2000.00271.x.
Diode laser (810 nm) may possess theoretical advantages over the argon blue-green laser (488 nm) for iridotomy/iridoplasty in an eye with oedematous cornea, such as the acute angle-closure glaucoma (AACG) patient, because of better diode laser tissue penetration in opaque media. We assessed the transmissibility of diode and argon lasers through corneas of varying clarity and evaluated the histopathological features of cornea and iris burns produced by these lasers.
The transmission of diode and argon lasers through human donor corneal buttons of three grades of clarity--clear, intermediate, and hazy--were compared. Corneal buttons of these varying levels of clarity were also treated with argon and diode lasers, with the beams deliberately focused onto the mid-stroma to assess their photothermal effects. Exposed pigmented irides from whole human eyes were treated directly with argon and diode lasers. The lasers were delivered via slit-lamp systems and the energy settings used were 1000 mW for argon and 980 mW for diode; spot sizes for both lasers were 100 microm, with exposure durations of 0.1 s. Light microscopy studies of these tissues were performed.
Transmissibility of diode laser in clear, intermediate, and hazy corneas were 89, 87 and 85% respectively and was significantly superior to argon laser (78, 73 and 70% respectively; P < 0.001, paired Student's t-test). Diode laser did not produce morphological changes in all three grades of corneas whereas argon-laser-treated hazy corneas showed photothermal damage. Both lasers produced deep iris burns, with the diode laser tending to produce deeper burns.
Our findings suggest that diode laser may be the ideal laser for iridotomy/iridoplasty in the AACG patient with hazy cornea.
对于患有角膜水肿的眼睛，如急性闭角型青光眼（AACG）患者，二极管激光（810纳米）在进行虹膜切开术/虹膜成形术时可能比氩蓝绿激光（488纳米）具有理论优势，因为二极管激光在不透明介质中对组织的穿透性更好。我们评估了二极管激光和氩激光透过不同透明度角膜的透射率，并评估了这些激光造成的角膜和虹膜烧伤的组织病理学特征。
比较了二极管激光和氩激光透过三种透明度等级（透明、中度、混浊）的人类供体角膜片的透射率。对这些不同透明度等级的角膜片也用氩激光和二极管激光进行处理，将光束故意聚焦于基质中部以评估其光热效应。对整个人类眼球暴露的有色虹膜直接用氩激光和二极管激光进行处理。激光通过裂隙灯系统发射，氩激光的能量设置为1000毫瓦，二极管激光为980毫瓦；两种激光的光斑大小均为100微米，曝光持续时间为0.1秒。对这些组织进行了光学显微镜研究。
二极管激光在透明、中度和混浊角膜中的透射率分别为89%、87%和85%，明显优于氩激光（分别为78%、73%和70%；P<0.001，配对学生t检验）。二极管激光在所有三个等级的角膜中均未产生形态学变化，而经氩激光处理的混浊角膜显示出光热损伤。两种激光均造成虹膜深层烧伤，二极管激光造成的烧伤往往更深。
我们的研究结果表明，对于角膜混浊的AACG患者，二极管激光可能是虹膜切开术/虹膜成形术的理想激光。
