Accuracy of Predictive Refraction in Combined Vitrectomy-Cataract Surgery for Epiretinal Membrane and Macular Hole

PURPOSE: To evaluate the accuracy of predictive refraction and the factors influencing the predictability in combined vitrectomy and cataract surgery. METHODS: We retrospectively investigated patients who received combined vitrectomy and cataract surgery for idiopathic epiretinal membrane (ERM) and macular hole (MH), followed up for a minimum of 6 months. Preoperative refraction, target refraction, postoperative refraction, predictive refraction error (target refraction - postoperative refraction), accuracy of predictive refraction error (predictive refraction error was within +/-0.5 diopter), intraocular pressure, axial length, central macular thickness, and tools that were used for intraocular lens power calculation (A-scan and IOL master) were assessed by analyzing medical records. RESULTS: A total of 176 eyes (including 132 idiopathic ERM cases and 44 MH cases) were included in this study. The accuracy of predictive refraction error was 60.8% at 6 months and there was no difference between the idiopathic epiretinal membrane group (59.8%) and the macular hole group (63.6%). There was no significant difference in predictive refraction error according to axial length and tools (IOL master vs A-scan). Predictive refraction error correlated positively with preoperative refraction (r = 0.227; p = 0.002). In the ERM group, predictive refraction error correlated negatively with both preoperative central macular thickness and the change in central macular thickness between, before, and 6 months after surgery (r = -0.211; p = 0.015 and r = -0.241; p = 0.005). CONCLUSIONS: The accuracy of predictive refraction error was approximately 60% in combined vitrectomy and cataract surgery. Postoperative refraction appeared to be myopia relative to target refraction with higher preoperative myopia and thicker preoperative central macular thickness. Hence, the intraocular lens power should be determined considering the above factors.

The Clinical Results of Hydrophobic Single-Piece Acrylic Intraocular Lenses after Cataract Surgery

PURPOSE: To report the results of the clinical use of single-piece acrylic intraocular lenses (IOLs; AcrySof(R), SA60AT, Alcon) compared with three-piece acrylic IOLs (AcrySof(R), MA60BM, Alcon) after cataract surgery. METHODS: We retrospectively analyzed data of the extent of IOL decentration and tilting measured with Scheimpflug camera (EAS-1000 anterior eye segment analysis system, Nidek) at 1 week, 1 month and 2 months after surgery, the difference in the preoperative predictive refraction and the postoperative actual refraction, and the higher order RMS (root mean square) value with WASCA wavefront analyzer (Carl Zeiss Meditec, Germany) between the two groups (SA60AT group: N=30 , MA60BM group: N=30). RESULTS: The extent of IOL decentration was statistically insignificant in both groups (p>0.05), but the amount of IOL tilting in the SA60AT group was significantly less than that in the MA60BM group at 1 week, 1 month and 2 months postoperatively (p<0.05). There was no statistically significant difference in the preoperative predictive refraction and the postoperative actual refraction between the two groups. The triangular coma aberrations and the higher order (HO) RMS values were, however, significantly less in the SA60AT group (p<0.05). CONCLUSIONS: The SA60AT IOLs provided a better postoperative centration and a smaller HO RMS value than the MA60BM IOLs. Based on these results, we expect that SA60AT IOLs will provide a better clinical outcome in the aspect of quality of vision.

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.

E valuation for the Differences of Predictive Refraction Among Three Types of Intraocular Lenses with Manufactu red A constant and Revised A constant

To compare the difference of predictive refraction among three types of PC-IOLs, we reviewed retrospectively 180 cataractous eyes that had undergone phacoemulsification and PC-IOL implantation by the same surgeon at 2 months postoperatively. The inclusion criteria consisted of the axial length ranging from 22 mmto 24.5 mm, the best corrected visual acuity better than 0.9 in Snellen chart and the astigmatism within+/-1 diopter at the time of postoperative 2 months. Patients were divided into 3 groups according to PCIOL types. Group 1 comprised of AMO(r) PhacoFlex SI30NB(71 eyes), group 2 of Acylsof(r) MA60BM(58 eyes), and group 3 of CILCO(r) PMMA single-piece MZ60BD(50 eyes).IOL power calculations were processed by SRKII with manufactured A constant and with revised A constant. There were no significant differences in predictive error within+/-1 diopter among different groups(P>0.05).With manufactured A constant, SI30NB with polypropylen haptics showed hyperopic shift in relative error. MZ60BD with a single-piece and narrowing haptic angle showed more myopic shift than MA60BM(P<0.05). But with revised A constant, there were no significant differences in myopic or hyperopic shift and showed more enhancement in the accuracy of predictive refraction than with manufactured A constant.