Comparison of three newer generation freely available intraocular lens power calculation formulae across all axial lengths.

Purpose: The aim of this study is to evaluate the accuracy of three newer generation formulae (Barrett Universal II, EVO, Hill-RBF 2.0) for calculation of power of two standard IOLs-the Acrysof IQ and Tecnis ZCB00 across all axial lengths. Methods: In this retrospective series, 206 eyes of 206 patients, operated for cataract surgery with above two IOLs over the last 6 months, were included in the study. Preoperative biometry measurements were obtained from LenstarLS900. By using recommended lens constants, the mean error for each formula was calculated and compared. Then, the optimized IOL constants were calculated to reduce the mean error to zero. Mean and median absolute errors were calculated for all eyes and separately for short (AL<22.5 mm), medium (22.5-24.5 mm), and long eyes (>24.5 mm). Absolute errors and percentages of eyes within prediction errors of ±0.25 D, ±0.50 D, ±0.75 D, and ±1.00 D were compared. Results: Prediction error with using recommended lens constants was significantly lower in the Barrett Universal II formula as compared to the other two formulae. However, after optimizing lens constants, there were no significant differences in the absolute errors between the three formulae. The formulae ranked by mean absolute error were as follows: Barrett Universal II (0.304 D), EVO (0.317 D), and Hill-RBF (0.322) D. There were no significant differences between absolute errors in the three formulae in each of the short-, medium-, and long-eye subgroups. Conclusion: With proper lens constant optimization, the Barrett Universal II, EVO, and Hill-RBF 2.0 formulae were equally accurate in predicting IOL power across the entire range of axial lengths.

Incision size changes after cataract surgery with intraocular lens implantation: comparison of 2 preloaded IOL implantation injectors.

PURPOSE: To compare incision size enlargement at different times of cataract surgery and visual outcomes after surgery in 2 different intraocular lens (IOL) delivery systems (Vivinex iSert and UltraSert Preloaded IOL Delivery System). SETTING: Tertiary care eye institution. DESIGN: Prospective nonrandomized comparison study. METHODS: All eyes had uneventful temporal clear corneal phacoemulsification cataract surgery. The surgery was done by standard direct horizontal chop with a bimanual irrigation aspiration of the cortex. The primary incision size was measured after clear corneal incision, after the completion of phacoemulsification, and after IOL implantation. RESULTS: The study comprised 276 eyes of 220 patients. The mean initial corneal incision was similar in both groups (2.2 mm). There was no significant difference in the mean incision size after phacoemulsification between the 2 groups (2.250 mm ± 0.068 mm [SD] vs 2.251 ± 0.066 mm [SD], P > .99). There was no significant difference in the mean (SD) incision size after IOL insertion between the 2 groups (2.367 ± 0.066 mm vs 2.369 ± 0.062 mm [SD], P = .815. The corrected distance visual acuity was 6/6 at 1 month in 80% of the participants in the UltraSert group and 86% in the Vivinex group. After adjusting for age, sex, grade of cataract, and IOL power, no significant difference was found in the magnitude of surgically induced astigmatism (SIA) in the Vivinex group compared with the UltraSert group (0.06, 95% CI, -0.11 to 0.24; P = .47). CONCLUSIONS: No significant difference was found in the change in the incision size, visual acuity, and SIA between UltraSert and Vivinex IOL delivery systems. This suggests that both IOL delivery systems are comparable in terms of post-IOL delivery incision enlargement for incisions of 2.2 mm.