Ray-tracing intraocular lens power calculation using anterior segment optical coherence tomography measurements

PURPOSE: To assess the efficiency of ray-tracing intraocular lens (IOL) power calculation with anterior segment optical coherence tomography (AS-OCT) in normal eyes with cataract. SETTING: Miyata Eye Hospital, Miyakonojo, Miyazaki, Japan. DESIGN: Case series. METHODS: The study comprised consecutive patients who had cataract surgery and obtained a corrected visual acuity of 0.15 logMAR or better postoperatively. Preoperatively, Placido topography and AS-OCT measurements were taken during a routine examination. The predicted postoperative refractions were obtained using 3 methods: the SRK/T formula with autokeratometry, ray-tracing calculation with Placido topography data, and ray-tracing calculations with AS-OCT measurement of both corneal surfaces. The refractive errors from the manifest refraction spherical equivalent were compared 1 month postoperatively, and the effects of corneal eccentricity and posterior corneal curvature were evaluated. RESULTS: Seventy patients (102 eyes) were enrolled. There was no significant difference in refractive errors (P=.89). The refractive error with the SRK/T formula was correlated significantly with corneal eccentricity (P=.0017); the ray-tracing calculations were unaffected. There was a weak correlation with the posterior corneal curvature in the ray-tracing calculations performed with Placido topography (P<.0002). CONCLUSION: The accuracy of the ray-tracing IOL power calculations using AS-OCT data was comparable to that of the conventional formula and minimized the effect of corneal eccentricity and posterior corneal curvature.