准分子激光原位角膜磨镶术后人工晶状体度数的计算方法

目的 验证准分子激光原位角膜磨镶(LASIK)术后人工晶状体度数的有效测量方法.方法 回顾性系列病例研究.收集在香港养和医院行LASIK手术8年或3个月后因白内障形成而行白内障超声乳化吸除术的患者28例(40只眼).利用临床既往数据计算得出K(K1)值以及由IOLmaster人工晶状体测量仪所测得K(K2)值,将K值输入SRK/T公式得出人工晶状体的度数.用K1与用K2预测术后屈光度组间比较采用配对t检验,用K1预测术后屈光度与术后3个月时实际屈光度组间比较采用秩和检验.结果 患者眼轴长度为(24.28～31.96)mm,平均为(28.06±1.98)mm.LASIK手术前的初始屈光度数(球镜当量)为(-3.13～-18.00)D,平均为(-10.44±3.93)D;K值为(41.40～46.90)D,平均为(43.57±1.47)D.最佳矫正视力:19只眼为1.0,10只眼为0.8,7只眼为0.6,4只眼为0.5.LASIK术后6个月的平均屈光度数(球镜当量)为(-2.83～+1.25)D,平均为(-0.32±0.95)D.超声乳化白内障吸除术前的平均屈光度数(球镜当量)为(-5.75～+1.13)D,平均为(-2.35±2.16)D.根据临床既往数据计算所得的K1平均值(KpreLASIK+RpreLASIK-RpostLASIK)为(27.60～40.70)D,平均为(34.62±3.56)D,由IOLmaster人工晶状体测量仪所测得的K2值为(32.39～43.53)D,平均为(38.04±2.45)D,两者间比较差异有统计学意义(t=-7.68,P=0.00).由K1值测得的人工晶状体度数的术后预计平均屈光度数(球镜当量)为(-3.69～0.61)D,平均为(-1.32±1.00)D;而由K2值测得的则为(-3.67～3.95)D,平均为(-0.60 ±1.84)D,两者差异有统计学意义(t=-2.40,P=0.02).超声乳化白内障吸除术后的平均屈光度数(3个月以上)为(-4.50～+1.75)D,平均(-1.10 ±1.51)D,与K1值测得的人工晶状体度数的术后预计平均屈光度数比较,两者差异无统计学意义(Z=1.20,P=0.23).超声乳化白内障吸除术后最佳矫正视力:20只眼为1.0,9只眼为0.8,5只眼为0.6,6只眼为0.5.结论 本研究所使用的人工晶状体度数的计算公式是准确而可行的.

Intraocular lens power calculation after corneal refractive surgery

Objectives To investigate the effective method for the calculation of intraocular lens power retrospectively from post-IASIK cases.Methods It was a retrospective case series.40 eyes of 28 patients(14 male and 14 Female)had the Phacoemulcification post-LASIK in HongKong Sanitorium & Hospital;the age ranged from 41.00 to 69.00 years ages,(50.68 ±6.56)years.LASIK was done from January,1997 to April,2005.Phacoemulcification was done from October,2000 to September,2005.Results Average axial length was(28.06 ±1.98)mm(rang from 24.28 to 31.96 mm).The initial refraction power (Spherical Equivalent,SE)before LASIK was from-3.13 to-18.00 D,(-10.44 ±3.93)D.K value pre-LASIK was 41.40 to 46.90 D,(43.57 ±1.47)D.The best corrected visual acuity(BCVA)preLASIK was 20/20 in 19 eyes,20/25 in 10 eyes,20/30 in 7 eyes and 20/40 in 4 eyes.The refraction power of 6 months post-LASIK(SE)was-2.83 to+1.25 D,(-0.32 ±0.95)D.The refraction power pre-phaco (SE)was-5.75 to+1.13 D.(-2.35±2.16)D.The calculated K1(KpreLASIK-RpostLASIK+RpreLASIK)was 27.60 to 40.70 D.(34.62±3.56)D.The K from the IOLmaster(K2)wag 32.39 to 43.53 D,(38.04±2.45)D.The target refraction of K1 was-3.69 to 0.61 D,(-1.32±1.00)D,the target refraction of K2 was-3.67～3.95 D,(-0.60±1.84)D.There was significant difference between these two target refraction,(t=-2.40,P=0.02).The refraction power of post-phaco(＞3 months)was -4.50 to+1.75 D,(-1.10±1.51)D.The BCVA post-Phaco was 20/20 in 20 eyes,20/25 in 9 eyes,20/30 in 5 eyes and 20/40 in 6 eyes.Conclusions The formula used in the study for the calculation of intraocular lens power is accurate and effective.