Establish A Class Of New Mathematic Calculated Model Of Intraocular Lens Power For Cataract Patients After Myopic Excimer Laser Corneal Refractive Surgery

Objective:To establish a totally new mathematical formula which can applied to calculate the IOL power for patients after myopic excimer laser corneal refractive surgery,and that can be used conveniently.Methods:A:The case had collected 250 patients(487eyes) after excimer laser corneal refractive surgery,we collect uncorrected visual acuity(UCVA),best corrected visual acuity(BCVA),corneal curvature (Keratom-etric curvuture),anterior chamber depth (ACD)and axial length (AL) both preopera-tive and postoperative.then calculate the degree of spherical equivalent (SEQ),and the amount of spherical equivalent degree the refractive surgery has changed(ΔSEQsp), all patients has been divided into low, medium, high, ultra-high four groups byΔSEQsp. B:with SRK/Tformula, using mathematical least square method to deal with the case under four groups ofΔSEQsp,and then get four intraocular lens calculation formula with four different coefficients(LLZW-a,LLZW-b,LLZW-c,LLZW-d).And then compar-ed the results with SRK/T formula and Haigis-L formula for people after excimer laser corneal refractive surgery.Results:l,low group:usingLLZW-a formula:Pa=A-2.439AL-0.883K,the means for intraocular lens were 23.13±1.04D,the means for SRK/T formula were20.76±1.22D,the degree was significantly decreased than LLZW-a formula results (P=0.000),the means for IOL degree by haigis were 23.16±1.34D, there was no statistic significant difference between Haigis and LLZW-a (P=0.928);2,moderate group:using LLZW-b formula:Pb=A-2.357AL-0.931K,the means for intraocular lens were 23.46±1.31D,the means for SRK/T formula were 20.77±1.48D,the degree was significantly decreased than LLZW-b formula results(P=0.000),the means for IOL degree by haigis were 23.47±1.90D,there was no statistic significant difference between Haigis and LLZW-b(P=0.943);3,height group:using LLZW-c formula:Pc=A-2.189AL-1.037K, the means for intraocular lens were 24.02±1.46D,the means for SRK/T formula were 20.70±1.50D,the degree was significantly decreased than LLZW-c formula results(P= 0.000),the means for IOL degree by haigis were 24.03±2.01D,there was no statistic significant difference between Haigis and LLZW-c(P=0.924).4,ultra-high group:using LLZW-d formula:Pd=A-2.058AL-1.135K,the means for intraocular lens were 24.71±1.61D,the means for SRK/T formula were20.72±1.59D,the degree was significantly decreased than LLZW-d formula results (P=0.000),the means for IOL degree by haigis were24.71±2.04D,there was no statistic significant difference between Haigis and LLZW-d(P=0.957).Conclusions:IOL calculation after myopic excimer laser corneal refractive surgery:1.The degree of LLZW-a, b, c, d formula was significantly increased than SRK/T formula.2.The degree of intraocular lens power by LLZW-a, b,c, d formula are approximately with the Haigis formula.3.The application of LLZW-a,b,c,d formula were not needs for special equipment and the parameters prerefractive surgery, only based on the cataract patient's immediately check parameters such as the cornea and axial length,then that can calculated the IOL power.LLZW-a, b, c, d formula may be an simplely and conveniently mathematical formula of intraocular Lens power calculation that can be conveniently used for cataract patients after myopic excimer laser corneal refraction surgery.