Parel J M, Ren Q, Simon G
Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami School of Medicine, Fla.
J Refract Corneal Surg. 1994 Sep-Oct;10(5):511-8.
Thermal shrinkage of stromal collagen is known to produce changes in the corneal curvature. We designed a novel, noncontact laser beam delivery system to perform laser photothermal keratoplasty.
The instrument consisted of a pulsed holmium:YAG laser (2.10-micrometer wavelength, 250-microsecond pulse width, 5-hertz repetition rate) coupled via a monofilament fiber to a common slit-lamp microscope equipped with a polyprism, an adjustable mask, and a projection lens. The system projected an 8-spot annular pattern of infrared laser energy on the cornea to achieve a thermal profile within the stroma and to attain controlled, predictable collagen shrinkage. The system produced treatment patterns of 8 to 32 spots of 150 to 600 microns diameter in concentric rings, continuously adjustable between 3 and 7 mm. The versatility of the system in creating different treatment patterns was tested on thermal paper and human cadaver eyes.
A uniform beam profile and different treatment patterns for myopia, hyperopia, and astigmatism were obtained. Myopic correction of 6.00 diopters was demonstrated on cadaver eyes. Corneal topography documented corneal flattening (> 6.00 D) with the following treatment parameters: each spot size on the cornea = 300 microns, radiant exposure of each spot = 18.0 J/cm2, number of pulses = 1, diameter of the treatment ring = 3 mm.
Noncontact slit-lamp microscope laser delivery system for laser photothermal keratoplasty provides flexible and precise selection of laser treatment parameters. It may improve the efficacy of the procedure.
已知基质胶原的热收缩会引起角膜曲率的变化。我们设计了一种新型的非接触式激光束传输系统来进行激光光热角膜成形术。
该仪器由一台脉冲钬:钇铝石榴石激光（波长2.10微米，脉冲宽度250微秒，重复频率5赫兹）通过单丝光纤与一台配备多棱镜、可调光阑和投影透镜的普通裂隙灯显微镜相连组成。该系统将红外激光能量的8点环形图案投射到角膜上，以在基质内形成热分布并实现可控的、可预测的胶原收缩。该系统产生直径为150至600微米的8至32个点的同心环治疗图案，可在3至7毫米之间连续调节。在热敏纸和人尸体眼睛上测试了该系统创建不同治疗图案的多功能性。
获得了均匀的光束分布以及用于近视、远视和散光的不同治疗图案。在尸体眼睛上证明了6.00屈光度的近视矫正。角膜地形图记录了在以下治疗参数下角膜变平（>6.00 D）：角膜上每个光斑大小 = 300微米，每个光斑的辐射曝光量 = 18.0 J/cm²，脉冲数 = 1，治疗环直径 = 3毫米。
用于激光光热角膜成形术的非接触式裂隙灯显微镜激光传输系统可灵活、精确地选择激光治疗参数。它可能会提高该手术的疗效。
