黏度5500 mPas硅油填充眼超声生物学测量的准确性

摘要

背景 硅油填充眼超声生物学测量的准确性和可行性是眼科诊疗过程中的难题,对硅油眼性白内障行超声乳化联合人工晶状体(IOL)植入术时IOL度数的计算造成困难.一些大型医院常采用光学测量仪IOLMaster实现对硅油填充眼的生物学测量,但其对屈光介质严重混浊的病例仍无法进行测量.曾有研究者采用超声改良法或眼轴分段测量法进行估算,但其研究结果可能由于硅油黏度的不同而差异较大.目的 探讨超声对黏度5 500 mPas硅油填充眼生物学测量的计算方法,为超声法对不同黏度硅油填充眼进行生物学测量提供方法学参考依据. 方法 采用B型超声仪于37℃下对高度分别为20、24和28 mm的平衡盐溶液进行测量,并与黏度5 500 mPas硅油的相应测量高度进行比较,以得到计算硅油眼实际眼轴长度(AL)的公式.收集于2012年5月至2014年3月在青岛市海慈医疗集团接受黏度为5 500mPas硅油填充治疗的复杂性视网膜疾病患者30例32眼,按实际AL分为AL＜26 mm组(16例18眼)和AL≥26 mm组(14例14眼),分别于硅油取出术前1d行B型超声、IOL Master测量AL,并于术后3个月用A型超声及B型超声测量AL.对不同方法测量的AL值进行差异比较和相关分析,并对手术前后受检眼玻璃体腔长度和屈光度进行比较.结果 B型超声波在黏度5 500 mPas硅油中的传播速度为1 023 m/s,超声波在硅油眼与正常玻璃体腔中测算AL的校正系数为0.668,校正AL=角膜顶点至晶状体后极或囊膜中央点距离+0.668×晶状体后极或囊膜中央点至黄斑距离.AL＜26 mm组和AL≥26 mm组受检眼用术前B型超声校正公式法、IOLMaster测量法、术后A型超声测量法和术后B型超声测量法测量的AL值的总体比较,差异均无统计学意义(F=0.108,P=0.955;F=0.011,P=0.998);硅油取出术前,B型超声校正公式法测量的AL值与IOLMaster测量法、术后B型超声测量法和术后A型超声测量法间测得的AL值均呈明显正相关(AL＜26 mm组:r=0.876、0.921、0.809,均P＜0.01;AL≥26 mm组:r=0.943、0.956、0.955,均P＜0.01).硅油取出术前1d,B型超声测量的玻璃体腔长度校正值为(20.78±2.13)mm,硅油取出术后3个月测量的玻璃体腔实际长度为(20.89±2.16) mm,二者间差异无统计学意义(t=0.795,P=0.219).受检眼中16眼行IOL植入术后平均屈光度为(-1.25±1.69)D,与术前保留的(-1.50±0.00)D比较,差异无统计学意义(t=0.585,P=0.284).结论 B型超声法对硅油填充眼的生物学测量准确、简便,用于临床的可行性较好.%Background The ultrasonography for silicone tamponade eye is a problem in diagnosis and treatment of eye diseases,especially for the calculation of intraocular lens (IOL) power.IOL Master is usually used to the biometric measurement of the silicone tamponade eye in well-equipped hospital,but it is still disabled in serious cataractous eyes.Corrective B or A-type ultrasound methods have been used for a fewer years,but these measured results are incomparable probably due to the difference of viscosity of silicone oils.Objective This study attempted to investigate the accuracy of B-type ultrasonography for ocular axial length (AL) measurement in silicone tamponade eyes.Methods The transmitting speed of ultrasonic wave in the silicone oil was determined by comparing the outcomes between balance solution mesuring and 5 500 mPas silicone oil,and a calculating formula for corrective ocular AL in 5 500 mPas silicone filled eyes was further established.Thirty-two eyes of 30 patients who received 5 500 mPas silicone oil tamponade due to complex retinal detachment were enrolled in Qingdao Hiser Medical Group from May 2012 to March 2014.The eyes were assigned to the AL＜26 mm group (18 eyes of 16 patients) and AL≥26 mm group (14 eyes of 14 patients).B-scan ultrasound and IOL Master were used to measure the AL before the removal of the silicone oil,and the Als were measured again using A-scan ultrasound and B-scan ultrasound 3 months after the removal of the silicone oil.The outcomes were compared and the correlations were evaluated among different measuring methods.The vitrous length values before and after removal of the oils,and the diopters before and after intraocular pressure (IOP) implantation were compared to varify the results of B-type sonography for 5 500 mPas silicone-tamponade eyes.Results The transmitting speed of sound wave in 5 500 mPas silicone oil was 1 023 m/second with the conversion factor 0.668 between silicon oil eyes and vitreous cavity,and the corrected formula for AL measurement was:the length form cornea apex to the posterior pole of lens or the center of the capsular membrane+ 0.668×the length form posterior pole of lens or the center of the capsular membrane to the macular area.No significnant differences were found in the AL values among the corrective-B scan,IOL Master method,postoperative Bscan method and A-scan method both in the AL＜26 mm group and the AL≥26 mm group (AL＜26 mm:F=0.108,P =0.955;AL ≥ 26 mm:F =0.011,P =0.998),and the AL values by corrective B-scan was significantly correlated with that by IOL Master,postoperative B-scan and A-scan,respectively (AL＜26 mm group:r =0.876,0.921,0.809,all at P＜0.01;AL ≥ 26 mm group:r =0.943,0.956,0.955,all at P＜0.01).The vitreous cavity depth was (20.78 ±2.13)mm by corrective B-scan in 1 day before the removal of silicone,and that in 3 months after removal of silicone was (20.89±2.16) mm,without statistical diference between them (t =0.795,P =0.219).The actual postoperative refraction in 16 eyes with IOL was (-1.25 ± 1.69) D,and preoperative refrection was (-1.50 ±0.00) D,the difference was not statistically significant (t =0.585,P =0.284).Conclusions The biometry of B-scan ultrasonography for silicone-tamponade eye is accurate and simple,with a good feasibility in clinical measurement.