硅油填充眼超声生物测量法的临床观察

Clinical results of ultrasound biometry in silicone oil-filled eye

目的探讨硅油填充眼超声生物测量法的临床效果。方法系列病例研究。根据超声测距原理，对相同高度的平衡盐溶液和硅油进行对比研究，计算出其间的测距比例常数（0．674），从而建立硅油填充眼矫正眼轴的测算公式，即公式=ab＋0．674×bc（a、b、c分别为角膜顶点、晶状体后极或囊膜中央点、黄斑表面）。然后，采用Vivid7型超声诊断仪对150例（150只眼）硅油填充眼取出硅油前后的眼轴和玻璃体腔前后径进行测量，根据眼轴的长度分为两组，即第1组患者的眼轴长度〈25mm，第2组患者的眼轴长度≥25mm。其中76只眼在硅油取出联合人工晶状体（IOL）植入术前，按Sanders retzlaff kraftT公式计算出IOL度数，将术后实际屈光状态与术前预见屈光状态进行比较。两组患者术前后眼轴长度、玻璃体腔前后径、屈光状态进行比较，采用配对t检验。结果150例（150只眼）硅油填充眼患者术后随访3个月，视网膜病变稳定。生物测量结果：第1组111只眼，硅油取出术前矫正眼轴长度为21．10—24．90mm，平均（22．77±1．00）mm；硅油取出术后眼轴长度21．00～24．70mm，平均（22．76±0．99）mm；两者之间的差异无统计学意义（t=0．518，P〉0．05）；111只眼取出硅油前与后玻璃体腔前后径的超声测量值分别为（26．57±2．14）mm和（17．90±1．38）mm，后者与前者的比值为0．67378。第2组39只眼，硅油取出术前矫正眼轴长度为25．00～30．58mm，平均（26．52±1．31）mm；硅油取出术后眼轴长度为25．00-30．59mm，平均（26．53±1．29）mm；两者之间的差异也无统计学意义（t=0．109，P〉0．05）；39只眼硅油取出前与后玻璃体腔前后径的超声测量值分别为（32．01±2．90）mm和（21．57±2．04）mm，后者与前者的比值为0．67395。两组76例（76只眼）IOL植入术后患者随访3个月以上，其术后实际屈光状态与术前预见屈光状态分别进行比较，差异均无统计学意义（t1=0．253，P1〉0．05；t2=0．209，P2〉0．05）。结论硅油填充眼的超声生物测量法准确、简便，临床应用效果好。

Objective To evaluate a method of ultrasound biometry in silicone oil-filled eye and its clinical results. Methods This was a series case study. According to the principle of measuring a distance with ultrasound, we compared the measured distance between a space filed with balanced salt solution and silicone oil at same height, to calculate a conversion factor （0. 674） between them. A formula for corrective axial length in silicone oil-filled eye was established. The formula = ab ＋ 0. 674 × be （ a, b and c standing for the apex of the cornea, the posterior pole of the lens or the center of the capsular membrane and the anterior surface of the macular, respectively）. The axial lengths of 150 silicone oil-filled eyes in 150 cases were then measured before and after silicone oil removal with Vivid 7 Dimension ultrasound. According to the axial length, they were divided into two groups, namely group 1 （the length 〈25 mm） and group 2 （the length1〉 25 mm）. In 76/150 eyes, before combined silicone oil removal and intraocular lens （IOL） implantation, the SRKT formula was used for intraocular lens calculation; the post-operative actual refraction was compared with the pre-operative predicted refraction and statistics analysis was made. Results The retinal condition of 150 silicone oil-filled eyes in 150 cases after 3 months＇ follow-up was stable after surgery. The results of the biometry were as follows. In the first group, the mean corrective axial lengths of 111 silicone oil-filled eyes before silicone oil removal was （22.77± 1.00） mm （ ranging from 21.10 to 24. 90 mm） ; the mean axial lengths after silicone oil removal was （22. 76 ± 0. 99） mm （ ranging from 21.00 to 24.70 mm）. The difference between them was not statistically significant （t = 0. 518,P 〉 0.05）. The vitreous cavity depth before and after silicone oil removal was （26. 57 ±2. 14） mm and（ 17. 90± 1.38） mm, respectively. The ratio of the latter to the former was 0. 673 78. In the second group, the mean corrective axial lengths of 39 silicone oil-filled eyes before silicone oil removal was （26. 52± 1.31 ）mm （ranging from 25.00 to 30.58 mm） ; the mean axial lengths after silicone oil removal was （26. 53 ± 1.29 ） mm（ ranging from 25.00 to 30. 59 mm）. The difference between them was not statistically significant （t = 0. 109, P 〉 0. 05 ）. The vitreous cavity depth before and after silicone oil removal was （32. 01±2. 90） mm and （21.57 ±2. 04）mm, respectively. The ratio of the latter to the former was 0. 673 95. In 76 eyes with IOL, the post-operative actual refraction after at least 3 months follow-up was compared with the pre-operative predicted refraction （ - 1.50 DS） in both groups. The differences between them were not statistically significant （ t1 = 0. 253, P1 〉 0. 05 ; t2 = 0. 209, P2 〉 0. 05 ） in each group. Conclusion Ultrasound biometry in silicone oil-filled eye is accurate and simple, and has good results in clinical measurement.