Tomographic Analysis of Anterior and Posterior and Total Corneal Refractive Power Changes After Femtosecond Laser-Assisted Keratotomy.

Abstract

To analyze the effect of penetrating femtosecond laser-assisted keratotomy (pFLAK) during laser lens surgery on anterior and posterior corneal astigmatism and total corneal refractive power (TCRP) astigmatism (CA_ant, CA_post, CA_TCRP) measured with Scheimpflug tomography. Prospective, interventional case series. This institutional study included 27 eyes of 23 patients (aged 65 ± 8 years) with low-to-moderate CA_TCRP determined with Scheimpflug tomography (Pentacam HR; Oculus, Wetzlar, Germany) after penetrating femtosecond laser-assisted keratotomy (pFLAK) and laser lens surgery. The CA_ant, CA_post, and CA_TCRP were determined before and 1 and 3 months after surgery. Vector analysis according to the Alpins method was used to calculate surgically induced astigmatism (SIA). The mean preoperative CA_ant (0.97 ± 0.30 diopter [D]) was significantly reduced to 0.63 ± 0.34 D (P < .001). SIA_ant was 0.71 ± 0.37 D. The CA_post showed no significant change, from preoperative 0.26 ± 0.12 D to 0.26 ± 0.10 D postoperatively (P = .625). In line with this finding, SIA_post was low (0.12 ± 0.07 D). The CA_TCRP showed similar results as CA_ant. pFLAKs planned according to Scheimpflug-based CA_TCRP result in a significant reduction of the CA_ant and CA_TCRP, but do not affect the posterior corneal curvature significantly, as measured by Scheimpflug tomography. Further research is required to develop a new valid nomogram for laser-assisted lens surgery.