Comparative Topographic and Tomographic Assessment of Post-LASIK Corneal Ectasia.

Purpose: To evaluate and compare the topographic and tomographic characteristics of post-laser in situ keratomileusis (LASIK) ectasia (PLE) with keratoconus (KC) and normal control eyes using the Sirius imaging system.

Methods: This comparative cross-sectional study included eyes with KC, PLE ectasia, and normal control eyes. All PLE cases developed ectasia following myopic LASIK. Normal control eyes were selected from refractive surgery candidates with normal preoperative corneal tomography and no evidence of ectasia during a postoperative follow-up period exceeding 1 year. Corneal topography and tomography were performed using the Sirius imaging system. Uncorrected and corrected distance visual acuities were recorded and expressed in decimal notation. Statistical analysis was performed using the Kruskal-Wallis test with post hoc Mann-Whitney U testing. Normality was assessed using the Shapiro-Wilk test. Due to non-normal distribution, nonparametric tests were used.

Results: A total of 56 eyes were analyzed. KC eyes demonstrated significantly steeper anterior keratometric values compared to PLE and normal control eyes (p < 0.001). PLE eyes showed lower anterior keratometric values compared to KC, but remained significantly different from normal controls (p < 0.001). Minimum corneal thickness was significantly reduced in both ectatic groups compared to normal controls (p < 0.001), with no statistically significant difference between KC and PLE eyes. Posterior tomographic indices were significantly elevated in both ectatic groups compared to normal controls (p < 0.001).

Conclusion: PLE demonstrates distinct topographic and tomographic characteristics compared to KC. Comprehensive corneal tomography is essential for accurate evaluation of post-LASIK ectasia.