Storm Eye Institute, Medical University of South Carolina, 167 Ashley Avenue, Charleston, SC 29425-5536, USA.
Ophthalmology. 2011 Mar;118(3):498-502. doi: 10.1016/j.ophtha.2010.06.042. Epub 2010 Oct 29.
To compare axial length measurements by contact and immersion techniques in pediatric cataractous eyes.
Prospective, comparative case series.
In this prospective study, 50 cataractous eyes of 50 children were enrolled. In bilateral cataract, only 1 eye was selected to avoid a correlation effect in statistical analyses.
Axial length was measured by both contact and immersion techniques for all eyes, randomized as to which to perform first to avoid measurement bias.
Axial length measured by contact and immersion techniques and the difference between contact and immersion technique axial length measurements.
Mean age±standard deviation at cataract surgery and at axial length measurement was 3.87±3.72 years. Axial length measurement by contact technique was significantly shorter as compared with immersion technique (21.36±3.04 mm and 21.63±3.09 mm, respectively; P<0.001). Axial length measurements using the contact technique were on an average 0.27 mm shorter than those obtained using the immersion technique. Forty-two eyes (84%) had shorter axial length when measured using the contact technique as compared with the immersion technique. Lens thickness measurement by contact technique was not significantly different from that of immersion technique (3.61±0.74 and 3.60±0.67 mm, respectively; P = 0.673). Anterior chamber depth measurement was significantly more shallow with the contact technique (3.39±0.59 mm and 3.69±0.54 mm, respectively; P<0.001). Intraocular lens power needed for emmetropia was significantly different (28.68 diopters [D] vs. 27.63 D; P<0.001).
Contact A-scan measurements yielded shorter axial length than immersion A-scan measurements. This difference was mainly the result of the anterior chamber depth rather than the lens thickness value. During intraocular lens (IOL) power calculation, if axial length measured by contact technique is used, it will result in the use of an average 1-D stronger IOL power than is actually required. This can lead to induced myopia in the postoperative refraction.
比较接触式和浸润式技术在小儿白内障眼中的眼轴测量值。
前瞻性、对照病例系列研究。
在这项前瞻性研究中，纳入了 50 名儿童的 50 只白内障眼。在双眼白内障中，仅选择 1 只眼进行测量，以避免统计分析中的相关性影响。
所有眼均采用接触式和浸润式技术进行眼轴测量，两种方法的测量顺序随机，以避免测量偏倚。
接触式和浸润式技术测量的眼轴长度以及接触式和浸润式技术测量的眼轴长度差值。
白内障手术时和眼轴测量时的平均年龄（标准差）为 3.87（3.72）岁。接触式技术测量的眼轴长度明显短于浸润式技术（分别为 21.36（3.04）mm 和 21.63（3.09）mm；P<0.001）。接触式技术测量的眼轴长度平均比浸润式技术短 0.27mm。与浸润式技术相比，42 只眼（84%）采用接触式技术测量时眼轴更短。接触式技术测量的晶状体厚度与浸润式技术无显著差异（分别为 3.61（0.74）mm 和 3.60（0.67）mm；P=0.673）。接触式技术测量的前房深度明显较浅（分别为 3.39（0.59）mm 和 3.69（0.54）mm；P<0.001）。用于正视眼的人工晶状体屈光度也显著不同（28.68 屈光度[D]比 27.63 D；P<0.001）。
接触式 A 扫描测量的眼轴长度短于浸润式 A 扫描测量。这种差异主要是由于前房深度而不是晶状体厚度值造成的。在人工晶状体（IOL）屈光度计算中，如果使用接触式技术测量的眼轴长度，将会导致使用比实际需要的平均 1 屈光度更强的 IOL 屈光度。这可能导致术后屈光度出现近视。
