Comparison Of Refractive Prediction Outcomes Based On Different Keratometric Parameters From The Iolmaster 700 And Pentacam Axl

To compare refractive prediction concurrently evaluating postoperative best corrected visual acuity (BCVA) with the outcomes obtained using different keratometric parameters, including standard keratometry (K) and total keratometry (TK) measured by the IOLMaster 700, and simulated keratometry (SimK), total corneal refractive power (TCRP), and equivalent keratometry reading at the 3-mm zone (EKR65) measured by the Pentacam AXL, with postoperative manifest refraction following cataract surgery.

Department of Ophthalmology, İstanbul Faculty of Medicine, İstanbul University, İstanbul Türkiye

This retrospective study included 95 eyes of 66 patients who underwent uncomplicated cataract surgery. All surgeries were performed by a single surgeon using the same surgical technique, and the same brand of monofocal intraocular lens was implanted in all cases. Preoperative biometric measurements were obtained using the IOLMaster 700 and Pentacam AXL. Intraocular lens power calculations were performed using the Barrett Universal II formula based on different keratometric parameters. Postoperative manifest refraction was recorded at 1 month. The absolute differences between preoperatively predicted and achieved postoperative refractive outcomes were calculated and compared among calculations based on the different keratometric parameters.

The mean age was 68.74±10.08 years (43–86). The mean preoperative BCVA was 0.71±0.53 logMAR and postoperative BCVA was 0.04±0.08 logMAR (p=0.003). The mean absolute difference between preoperatively predicted and achieved postoperative refractive outcomes was 0.52 ± 0.43 D for K, 0.56 ± 0.44 D for TK, 0.56 ± 0.44 D for SimK, 0.51 ± 0.39 D for TCRP, and 0.53 ± 0.41 D for EKR65. The lowest mean absolute difference was observed with TCRP, whereas the highest values were noted with TK and SimK. Friedman analysis demonstrated no statistically significant overall difference among the keratometric parameter based calculations (p = 0.087). Pairwise comparisons revealed a significant difference only between K  and TK based calculations (p = 0.002).

Keratometric parameters obtained from the IOLMaster 700 and Pentacam AXL demonstrated comparable agreement with postoperative manifest refraction. Although TCRP demonstrated the lowest mean absolute difference, no significant overall difference was observed among the evaluated parameters. However, a significant difference was found between K and TK based calculations. Overall, the different keratometric measurements provided similar refractive prediction performance in routine cataract surgery.