A超测量硅油填充眼眼轴及人工晶状体度数的临床评价

Clinical evauation on axial length and intraocular lens power measurement in silicone oil- filled eyes using A -scan ultrasound

目的评价A超经修正后测量硅油填充眼眼轴及人工晶状体（IOL）度数的准确性。方法应用我院现有的法国QUANTELMEDICAL公司的CompattachIIA／B超声仪采用实验的方法对超声波在纯Ox5700型硅油、患者眼中取出的硅油及平衡盐溶液中的传播速度进行测量及比较，进而对眼轴值进行修正，最终推算出准确的人工晶状体度数。选取25例行玻璃体切割伴硅油填充术的患者，应用公认0x5700型硅油的测量值对患眼进行眼轴的测量，再用我们实验所得到的测量值分别对患眼进行坐位及平卧位的眼轴测量，最后将坐位时测出的跟轴长度代入SRKⅡ公式计算拟植入的人工晶状体度数。行硅油取出术联合白内障摘除＋人工晶状体植入术。术后3个月测量患眼的眼轴、最佳矫正视力及屈光状态。对手术前后眼轴长度及最佳矫正视力进行对比，将术后屈光状态与术前预期值比较。结果纯Ox5700型硅油的比色杯宽度为（31．440±0．011）mm，患眼中取出硅油的比色杯宽度为（31．420±0．047）mm，两者间差异无统计学意义（P〉0．05）。平衡盐溶液的比色杯宽度为21．07mm。取油前，硅油填充眼的玻璃体腔的传播速度设置为990m／s时的患眼平均眼轴长度为（23．219±0．125）mm。传播速度设置为1027in／s时坐位测量患眼平均眼轴长度为（24．103±0．135）mm，平卧位患眼平均眼轴长度为（24．116±0．128）mm。取油后患眼平均眼轴长度为（24．018±0．135）mm。硅油的传播速度设置为1027m／s时坐、卧位测量的眼轴值同取油后患眼的眼轴值差异无统计学意义（P〉0．05）。传播速度设置为990m／s时的测量值与取油后眼轴长度及传播速度设置为1027m／s时测量的眼轴长度差异有统计学意义（P〈0．05）。手术后屈光度与术前预期值差值平均为（-1．50±2．00）D，差异无统计学意义（P〉0．05）。结论A超经修正后可准确测量硅油填充眼的眼轴长度，进而准确推算出硅油填充眼的IOL度数，A超测量硅油填充眼眼轴及IOL度数是相对准确、安全、方便的方式，但各医院应对自身的仪器及材料进行实验测量，进而得出更加适合本院的实验数值。

Objective To evaluate the accuracy of axial length and intraoeular lens （IOL） measurement in silicone oil -filled eyes using A -scan ultrasound. Methods The cuvette was put with the silicone oil taken from the patients＇ eyes, pure silicone oil and balanced salt solution. The speed of ultrasonic wave in these solvent was measured with empir- ical method using Compat tach II A/B acoustic instrument of French QUANTEL MEDICAL company. Then the measured axial length was corrected to evaluate the accurate power of IOL. 25 patients who had vitreetomy and silicone oil filled surgery were collected. Firstly, using the recognized acoustic speed of Ox5700 to measure the axial length of the sick eye. Secondly, using the speed by our experiment to measure the sick eye in sitting position and in supine position. Fi- naly, the power of IOL was then calculated through SRK II formula by the axial length in sitting position. They received silicone oil extraction and cataract phacoemulsifieation and IOL implantation in one operation. 3 months after surgery, all eyes were reexamined and the actual axial length were measured again. The eye axial length and the best correct visual a- cuity were compared before and after the operation. The postoperative refraction and preoperative expected refraction was compared. Results The mean width of colorimetric cuvettes filled with pure Ox5700 silicone oil was （ 31. 440 ± 0.011 ）ram, that filled with the oil taken from patients＇ eyes was （31.420 ±0. 047） mm. There was no difference between them. The width of colorimetric cuvettes filled with the balanced salt solution was 21.07 mm. The recognized acoustic speed of Ox5700 silicone oil was 990 m/s. Before the surgrey, the mean axial length under the acoustic speed of 990 m/s in sili- cone oil tamponade eyes was （23. 219 ±0. 125） mm. The mean axial length under the acoustic speed of 1 027m/s in sili- cone oil tamponade eyes was （24. 103 ±0. 135） mm in sitting position and was （24. 116 ±0. 128） mm in supine posi- tion. After the surgery, the mean axial length of the sick eye was （24. 018±0. 135） ram. There was no difference be- tween them when the acoustic speed of 0x5700 silicone oil was 1 027 m/s. There was a significant difference between them when the acoustic speed of Oxane5700 silicone oil was 990 m/s. The mean difference between postoperative refrac- tion and preoperative expected refraction was （ - 1.50± 2.00） D. There was no diference between them. Conclusion A - scan ultrasound can measure the axial length accurately with corrected the speed in the silicone oil - filled eyes and then ean calculate the IOL diopter. A -scan ultrasound is accurate, safe and convenient in measuring the IOL power in silicone oil temponade eye. According to different hospitals, techniques and matetials, different experimental data should be worked out to make patients to have their own best corrected visual acuity.