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

PURPOSE

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, CA, CA) measured with Scheimpflug tomography.

DESIGN

Prospective, interventional case series.

METHODS

This institutional study included 27 eyes of 23 patients (aged 65 ± 8 years) with low-to-moderate CA determined with Scheimpflug tomography (Pentacam HR; Oculus, Wetzlar, Germany) after penetrating femtosecond laser-assisted keratotomy (pFLAK) and laser lens surgery. The CA, CA, and CA 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).

RESULTS

The mean preoperative CA (0.97 ± 0.30 diopter [D]) was significantly reduced to 0.63 ± 0.34 D (P < .001). SIA was 0.71 ± 0.37 D. The CA 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 was low (0.12 ± 0.07 D). The CA showed similar results as CA.

CONCLUSION

pFLAKs planned according to Scheimpflug-based CA result in a significant reduction of the CA and CA, 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.