Effect of Posterior Corneal Cylinder on Toric IOL Calculation After Laser Refractive Surgery
Narrative Responses:
Purpose
To compare pre- and post myopic laser refractıve surgery astigmatic, keratometric and pachymetric measurements performed with Scheimpflug camera.
Methods
The Intralase femtosecond laser (AMO Inc, Irvine, CA) was used to create the flap in all eyes that underwent LASIK. All eyes underwent wavefront-guided LASIK with MEL 80 excimer laser (Carl Zeiss, Jena, Germany) for the correction of myopic astigmatism. 46 eyes of 23 patients were included in the study. The minimum required follow-up was 6 months after LASIK. Each eye was evaluated by Scheimpflug camera imaging (Pentacam, Wetzlar, Germany) before and after surgery.
Results
The mean K and corneal thickness decreased significantly after LASIK (p<0.05). The effect of posterior corneal cylinder increases after myopic laser refractive surgery for toric IOL placement. Among different equivalent K readings under 1.0mm, 2.0mm, 3.00mm and 4.5 mm zones, the mean lower equivalent K readings were closest to the benchmark value. However, there was a high variability. The mean sim K given by Pentacam was higher than the mean clinical history method value (p<0.05). The mean true net power was significantly lower than the value obtained with the clinical history method (p<0.05).
Conclusion
The lower K readings were tended to be closest to the benchmark value. Toric IOLs may overcorrect the corneal astigmatism after laser refractive surgery.