Hoffmann P C, Hütz W W, Eckhardt H B, Heuring A H
Augenklinik, Kreiskrankenhaus Bad Hersfeld.
Klin Monbl Augenheilkd. 1998 Sep;213(3):161-5. doi: 10.1055/s-2008-1034967.
Ultrasound biometry for axial length measurement may be performed either by directly putting the probe on the cornea or by using a water immersion technique. Our goal was to examine whether there are unsystematic differences between both techniques present besides systematic differences that can be compensated by adjusting calculation formula constants.
PATIENTS, MATERIALS AND METHODS: We examined 288 patients in a prospective, randomized trial. There was no ocular pathology present beside cataract. Axial lengths < 21 mm and > 27 mm were excluded. We calculated which IOL power would have given the desired refractive result by using the postoperative refraction and data of the lens implanted.
A systematic difference between both techniques is present. With the contact technique, axial length is measured 0.15 mm shorter. This requires adjustment of formula constants. Furthermore, there is an unsystematic difference that leads to 18% greater calculation errors (difference between IOL calculated preoperatively and ideal IOL) with the contact technique. Mean absolute error was 0.43 +/- 0.38 dpt for the immersion group and 0.53 +/- 0.48 dpt for the contact group.
To minimize postoperative refractive errors, ultrasound biometry using immersion technique should be preferred.
用于眼轴长度测量的超声生物测量法既可以通过将探头直接置于角膜上进行，也可以采用水浸技术。我们的目标是研究除了可通过调整计算公式常数来补偿的系统差异之外，这两种技术之间是否还存在非系统性差异。
患者、材料与方法：我们在一项前瞻性随机试验中对288例患者进行了检查。除白内障外无眼部病变。排除眼轴长度<21mm和>27mm的患者。我们利用术后验光结果和所植入晶状体的数据计算出哪种人工晶状体度数能产生预期的屈光效果。
两种技术之间存在系统差异。采用接触式技术时，测量的眼轴长度短0.15mm。这需要调整公式常数。此外，还存在非系统性差异，导致接触式技术的计算误差（术前计算的人工晶状体与理想人工晶状体之间的差异）大18%。水浸组的平均绝对误差为0.43±0.38屈光度，接触组为0.53±0.48屈光度。
为使术后屈光误差最小化，应优先选用水浸技术进行超声生物测量。
