Toric IOL Refractive Results Determined in Part by Scheimpflug Corneal Tomography
Total corneal refractive power (TCRP) as determined by the OCULUS Pentacam is defined by both anterior and posterior corneal astigmatism. TCRP should yield superior refractive results compared to those obtained using automated keratometry based on anterior astigmatism alone.
A prospective study of the refractive results of 106 consecutive single-piece AcrySof Toric IOL cases was accomplished. Preoperative variables of axial length and average keratometry were obtained by IOL Master and used to determine the IOL’s spherical power. The values of TCRP as determined by the Pentacam were entered as keratometry readings into Alcon’s Toric IOL Calculator to determine the magnitude of IOL astigmatic power for cylinder reduction. Intraoperative IOL orientation was accomplished using Alcon’s VERION Microscope Measurement Marker (MMM) system. IOL orientation estimates and manifest refractions were accomplished 2 months after surgery.
Diopter (D) amount of average preoperative astigmatism as determined by TCRP was 1.61 ± 0.84. The mean postoperative spherical equivalent was -0.06 D ± 0.36 and mean refractive cylinder was -0.38 ± 0.42 D. Respective with-the-rule (WTW), against-the-rule (ATR) and oblique (O) mean refractive cylinders were similar at: -0.47 ± 0.36, -0.40 ± 0.38, and -0.34 ± 0.48.
Components of the IOL Master, Pentacam, Toric IOL Calculator, and VERION MMM combined to provide a useful system which yielded accurate and consistent toric IOL performance.