Hitzenberger C K, Drexler W, Dolezal C, Skorpik F, Juchem M, Fercher A F, Gnad H D
Institut für Medizinische Physik, Universität Wien, Austria.
Invest Ophthalmol Vis Sci. 1993 May;34(6):1886-93.
To examine the applicability of the recently developed laser Doppler interferometry technique for measuring the axial length of cataract eyes in a realistic clinical situation. To determine the performance of the instrument as a function of cataract grade. To compare the results to those of ultrasound methods.
A total of 196 cataract eyes of 100 patients were examined. The axial eye length was determined by laser Doppler interferometry and by two different ultrasound techniques, the applanation technique and the immersion technique. The cataract grade was determined by a commercial instrument that measures backscattered light.
Laser Doppler interferometry worked very well except in the cases of the highest cataract grades (4% of the eyes of this study were not measurable because of a too-high lens density). Only 3.5% of the other eyes were not measurable because of fixation problems of the patients. The precision of laser Doppler interferometry is not influenced by the cataract grade (except the highest grade). The standard deviation of the geometric eye length is approximately 20 microns. Linear regression analysis revealed a very good correlation of laser Doppler interferometry and ultrasonic measurements, but a systematic difference was found. The eye lengths measured by laser Doppler interferometry were about 0.18 mm longer than those measured by the immersion technique and about 0.47 mm longer than those measured by the applanation technique.
These differences are attributed to the laser Doppler interferometry results including the retinal thickness and indentation of the cornea by the applanation technique. The main advantages of the laser Doppler interferometry technique are high precision, high accuracy, and more comfort for the patient because it is a noncontact method, anesthesia is unnecessary, and the risk of corneal infection is avoided.
研究最近开发的激光多普勒干涉测量技术在实际临床情况下测量白内障患者眼轴长度的适用性。确定该仪器作为白内障分级函数的性能。将结果与超声测量结果进行比较。
对100例患者的196只白内障眼进行检查。通过激光多普勒干涉测量法以及两种不同的超声技术（压平技术和浸入技术）确定眼轴长度。通过一种测量后向散射光的商用仪器确定白内障分级。
激光多普勒干涉测量法效果良好，除了白内障分级最高的情况（本研究中4%的眼睛因晶状体密度过高无法测量）。由于患者的固视问题，其他眼睛中只有3.5%无法测量。激光多普勒干涉测量法的精度不受白内障分级影响（最高分级除外）。眼球几何长度的标准差约为20微米。线性回归分析显示激光多普勒干涉测量法与超声测量有很好的相关性，但发现存在系统差异。激光多普勒干涉测量法测得的眼轴长度比浸入技术测得的长约0.18毫米，比压平技术测得的长约0.47毫米。
这些差异归因于激光多普勒干涉测量结果包括视网膜厚度以及压平技术引起的角膜压痕。激光多普勒干涉测量技术的主要优点是精度高、准确性高，对患者更舒适，因为它是一种非接触方法，无需麻醉，避免了角膜感染风险。
