The deviation between achieved net corneal thinning and predicted lenticule thickness after keratorefractive...

The primary objective of this study was to assess the discrepancy between the achieved net corneal thinning following during Keratorefractive Lenticule Extraction (KLEx) surgery and the preoperatively predicted lenticule thickness.

This retrospective study included data from KLEx procedures performed at our institution between January 2022 and June 2024. Corneal pachymetry measurements obtained preoperatively and postoperatively using the Scheimpflug based imaging system (Pentacam), were reviewed. These findings were compared to the surgical read out parameters by the Visumax500 femtosecond laser system (Carl Zeiss Meditec). Statistical analysis was conducted using SPSS software (version 22.0, IBM). For data sets comparisons were made using the Paired Samples T-test.

The analysis included 66 eyes from 66 patients, with a mean age of 29.4 years. The average preoperative central corneal thickness measured at the pupil center was 556.53 microns, which decreased to 484.92 microns postoperatively (p < 0.05). Similarly, the average apex corneal thickness changed from 557 microns to 486.53 microns following surgery (p < 0.05). The mean achieved reduction in corneal thickness was 70.47 microns, whereas the mean predicted reduction based on surgical parameters was 86.31 microns (p < 0.05). The average deviation between predicted and lenticule thickness and achieved net corneal thinning were calculated as 13.12 ± 7.86 microns. The difference was significantly higher in the patients with higher spherical eror but not correlated with corneal thickness or keratometric data.

Post-KLEx measurements demonstrated that actual stromal tissue removal was consistently less than preoperative estimates from the VisuMax 500. The magnitude of refractive correction also differed from values reported in the literature, suggesting possible variability related to device characteristics and population differences.