Vogel A, Dlugos C, Nuffer R, Birngruber R
H. Wacker Laboratory of Medical Laser Applications, University Eye Hospital Munich, Germany.
Lasers Surg Med. 1991;11(4):331-40. doi: 10.1002/lsm.1900110404.
The spectral dependence of the optical properties of human sclera adjacent to the limbus was investigated and related to the potentials of transscleral photocoagulation. The total transmission, absorption, and reflection, as well as the angular distribution of the transmitted and reflected light were measured at five laser wavelengths (442 nm, 514 nm, 633 nm, 804 nm, and 1,064 nm), both for noncontact and contact applications. Absorption and scattering coefficients were determined using the Kubelka-Munk model for light propagation through a scattering tissue. The scleral transmission is only 6% at 442 nm but increases to 35% at 804 nm and to 53% at 1,064 nm. The absorption is high at short wavelengths with 40% at 442 nm but it is only 6% at 804 nm and 1,064 nm. The reflection is generally higher than 40% and shows little wavelength dependence. The transmitted light is scattered diffusely at short wavelengths, but at 804 nm and 1,064 nm it exhibits a fairly narrow angular distribution in forward direction. Fiber contact leads to an increase of transmission, with a factor of 3.5 at 442 nm, of 2.0 at 804 nm, and 1.5 at 1,064 nm. Our results indicate that the diode laser (804 nm) and the Nd:YAG laser (1,064 nm) with contact delivery are best suited for transscleral photocoagulation.
研究了角膜缘附近人巩膜光学特性的光谱依赖性，并将其与经巩膜光凝的潜力相关联。在五个激光波长（442纳米、514纳米、633纳米、804纳米和1064纳米）下，分别针对非接触和接触应用测量了总透射率、吸收率和反射率，以及透射光和反射光的角分布。使用Kubelka-Munk模型确定光在散射组织中传播时的吸收系数和散射系数。巩膜在442纳米处的透射率仅为6%，但在804纳米处增加到35%，在1064纳米处增加到53%。短波长处的吸收率很高，442纳米处为40%，但在804纳米和1064纳米处仅为6%。反射率通常高于40%，且几乎没有波长依赖性。短波长处的透射光呈漫散射，但在804纳米和1064纳米处，它在向前方向表现出相当窄的角分布。光纤接触会导致透射率增加，442纳米处增加3.5倍，804纳米处增加2.0倍，1064纳米处增加1.5倍。我们的结果表明，采用接触式传输的二极管激光（804纳米）和Nd:YAG激光（1064纳米）最适合经巩膜光凝。
