Whitacre M M, Mainster M A
Department of Ophthalmology, University of Kansas Medical Center, Kansas City 66103.
Am J Ophthalmol. 1990 Jul 15;110(1):33-8. doi: 10.1016/s0002-9394(14)76934-x.
Three patients suffered photic or thermal laser injuries at unintended sites because of reflection from gas-fluid interfaces in eyes containing gas. Fresnel's equations predict the amount of light transmitted or reflected at optical interfaces. Application of Fresnel's equations demonstrate that significant laser reflection occurs at gas-fluid or fluid-gas interfaces, especially at high angles of incidence. Photocoagulation across gas-fluid or fluid-gas interfaces should be avoided to reduce the risk of unintended damage from reflected light. If photocoagulation must be performed across an interface, the surgeon should minimize the angle of incidence of the treatment laser beam, use a divergent beam, and consider the location and intensity of the reflected beam. Because of the higher phototoxicity of blue light, photocoagulation with blue-green lasers across gas-fluid or fluid-gas interfaces is undesirable. Proper polarization of the treatment laser beam may significantly reduce laser reflectance.
三名患者因含气眼内气液界面的反射，在非预期部位遭受了光或热激光损伤。菲涅耳方程可预测光在光学界面的透射或反射量。应用菲涅耳方程表明，在气液或液气界面会发生显著的激光反射，尤其是在高入射角时。应避免跨气液或液气界面进行光凝，以降低反射光造成意外损伤的风险。如果必须跨界面进行光凝，外科医生应尽量减小治疗激光束的入射角，使用发散光束，并考虑反射光束的位置和强度。由于蓝光的光毒性较高，不建议使用蓝绿激光跨气液或液气界面进行光凝。治疗激光束的适当偏振可显著降低激光反射率。
