矫正角膜散光对人工晶状体计算的影响
【摘要】 目的:分析白内障术中矫正角膜散光对人工晶状体度数预测的影响。方法:选择老年性白内障患者35例35眼,行上方切口超声乳化联合PMMA人工晶状体植入术后角膜散光减少,测量术前和术后3mo的角膜曲率及屈光状态。比较SRKⅡ,SRK/T,HolladayⅠ公式在使用术前和术后角膜曲率值计算的绝对预测误差。结果:手术前后平均角膜曲率增加0.30±0.81D,角膜散光度数减少0.70±0.71D,都有统计学意义(P<0.05),两者的相关性为(r=0.554,P<0.01)。SRKⅡ,SRK/T,HolladayⅠ使用术前角膜曲率计算的绝对预测误差中位数分别为0.85D,0.73D,0.78D,公式间无统计学差异(χ2=4.474,P>0.05);使用术后角膜曲率计算则分别为0.72D,0.54D,0.46D,有统计学差异(χ2=7.758,P<0.05);3代公式在两种计算方法下结果有有统计学差异(Z= 2.208,2.273,P<0.05)。结论:矫正角膜散光会引起角膜屈光度变化,导致人工晶状体度数的预测误差增大,计算公式尤其是3代公式的准确性下降,有必要对公式进行相应调整优化。
【关键词】 角膜散光;角膜平均曲率;人工晶状体公式核心期刊论文发表
Abstract AIM: To analyse the influence of correcting corneal astigmatism on the accuracy of intraocular lens power prediction after cataract surgery. METHODS: Thirtyfive cases of agerelated cataract 35 eyes were selected, the corneal astigmatism was reduced after phacoemulsification with superior incision and PMMA intraocular lens implantation. The keratometry was measured before operation and three months postoperatively,then the absolute forecast error of SRK Ⅱ, SRK/T, Holladay Ⅰ formula with preoperative and postoperative corneal curvature were compared.RESULTS: The average corneal curvature was increased by 0.30±0.81D (t=2.205, P<0.05),the corneal astigmatism was decreased by 0.70±0.71D after operation(t=5.846, P<0.01),there was correlation between them(r=0.554, P<0.01 ).The absolute predict errors of SRKⅡ,SRK/T and Holladay Ⅰ formulas using preoperative curvature was respectively 0.85D,0.73D and 0.78D, there was no significant difference (χ2=4.474,P>0.05). The absolute predict error using postoperative curvature was respectively 0.72D,0.54D and 0.46D,SRKⅡ indicated statistical difference from other formulas (χ2=7.758,P<0.05). The third theoretical formula had statistical difference from using preoperative and postoperative curvature(Z=2.208,2.273,P<0.05).CONCLUSION: Correcting the corneal astigmatism may cause the changes in corneal refraction, which leads to the error of the intraocular lens prediction increase, especially the accuracy of the third generation formula decrease, so it is necessary to adjust and optimize the formula accordingly.
KEYWORDS:corneal astigmatism;corneal curvature;intraocular lens power formulas
0引言核心期刊论文发表
研究证实减少白内障术后散光可以有效提高视觉质量[1],利用手术切口矫正术前角膜散光成为普遍采用的方法[2],但角膜的屈光变化导致人工晶状体度数的计算误差并未受到临床重视,我们选择相关病例比较这种影响,现报告如下。
1对象和方法
1.1对象 随机选择200907/200912在我院行超声乳化并人工晶状体植入术的老年性白内障患者35例35眼,男21例,女14例,平均年龄68.2±9.7岁,无明显角膜病变和手术并发症,术后角膜散光度数减少。核心期刊论文发表
1.2方法 使用IOLMaster校准的A超(AVISO,光太公司)测量眼轴,电脑验光仪(KR8800,托普康公司)测量术前和术后3mo的角膜曲率,并联合综合验光仪(CV3000,托普康公司)确定术后验光结果。使用AVISO内置SRKⅡ,SRK/T,Hoffer Q,HolladayⅠ公式分别计算绝对预测误差(预测误差=预测屈光度术后实际屈光度)。采用上方角膜缘3平面主切口,3∶00位辅助切口,连续环形撕囊,完成晶状体超声乳化(Millennium,博士伦公司)摘出后用5.5mm穿刺刀(爱尔康公司)扩大角巩膜缘切口,囊袋内植入PMMA人工晶状体。术后抗生素、激素滴眼1mo。
统计学分析:采用SPSS 13.0统计软件包。手术前后同参数比较用配对t检验,组间比较用MannWhitney检验,组内比较用Friedman检验。数据结果以±s或M表示,P<0.05为差异有统计学意义。核心期刊论文发表
2结果
2.1一般情况 眼轴为24.02±2.45mm。手术前后平均角膜曲率增加0.30±0.81D,角膜散光度数减少0.70±0.71D,都有统计学意义(P<0.05),两者的相关性为(r= 0.554,P<0.01)。角膜散光J0变化0.12±0.52D,J45为 0.21±0.58D,J45的差异有统计学意义(P<0.05,表1)。
2.2对人工晶状体度数计算的影响 公式SRKⅡ,SRK/T,HolladayⅠ在使用术前角膜曲率计算的绝对预测误差中位数分别为0.85D,0.73D,0.78D,公式间差异无统计学意义(χ2=4.474,P>0.05)
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