The Evaluation of the Difference between the Calculated Estimated Post-operative Refraction and the Real Post-operative Refraction for Five Types Intraocular Lenses

PURPOSE: To evaluate and compare the difference of predictive post-operative refraction preoperatively and real post-operative refraction among five types of intraocular lens. METHODS: We reviewed retrospectively 567 cataractous eyes that had undergone phacoemulsification or ECCE with posterior chamber intraocular lens (IOL) implantation by the same surgeon. Applied IOLs were AMO(R) Phacoflex(R) II SI40NB, Acrysof(R) MA60BM, Sensar(TM) AR40e, CeeOn(TM) 811B and CeeOn(TM) 720A. Prediction of post-operative refraction (predictive refraction) was calculated by the SRK/T formula with manufactured A constant. Post-operative manifest refraction (real refraction) was done at least 2 months postoperatively. We compared the difference between the predictive refraction and the real refraction by paired t-test. RESULTS: Total studied eyes were 390 eyes. In all groups, more myopic shift were observed than predicted. In AMO(R) Phacoflex(R) II SI40NB group, statistically significant difference was seen in postoperative manifest refraction over the predictive refraction as much as mean 0.46 diopter myopically (p<0.05, paired t-test), but others were not. In the AR40e implanted group, the error of predictive refraction was the smallest among groups. CONCLUSIONS: Prediction of postoperative refractive state was influenced by various clinical factors. Using a revised A constant, predictive error would be decreased. We recommend that every cataract surgeon had better have one's original A constant over each IOL and A constant may be revised when major surgical or biomedical measurement settings were changed.

Posterior Capsular Opacification and Nd: YAG Laser Capsulotomy in 811B, SI40NB, MA60BM Intraocular Lens

PURPOSE: To compare the incidence and the interval between the development of posterior capsular opacification (PCO) and Nd: YAG laser capsulotomy among patients implanted with a 811B, SI40NB, and MA60BM intraocular lens METHODS: One hundred ninty eyes of 157 patients who had undergone implant surgery with 811B, SI40NB, and MA60BM intraocular lens at the Presbyterian Medical Center were studied retrospectively. We compared the postoperative best corrected visual acuity, the incidence and the time interval between the development of PCO and laser capsulotomy, and the total energy used in laser capsulotomy among three intraocular lens groups. RESULTS: The incidence of development of PCO was 26.9% in 811B, 23.8% in SI40NB, and 10% in MA60BM groups, showing that incidence was significantly lower in the MA60BM group as compared to 811B (P=0.0016) or SI40NB (P=0.0056) group. The 811B group induced PCO earlier than SI40NB group. The energy used in Nd: YAG laser capsulotomy was lower in 811B than that in SI40NB or MA60BM. CONCLUSIONS: The incidence of posterior capsular opacification and that of Nd: YAG laser capsulotomy were found to be significantly lower in the MA60BM group than those in 811B or SI40NB group.