PURPOSE: To investigate agreement between the predicted ablation depth calculated by the EX500 excimer laser (Wavelight Laser Technologie AG, Erlangen, Germany) and the measured ablation depth in eyes that have undergone femtosecond laser-assisted LASIK (FSLASIK) for myopia. METHODS: Corneal thickness was measured with a rotating Scheimpflug camera preoperatively and 3 months postoperatively and the difference between these values was defined as the measured ablation depth. The difference between the predicted and the measured ablation depth was defined as the difference in ablation depth (ΔAD). RESULTS: In 85 eyes of 85 patients, no statistically significant difference was detected between the mean predicted ablation depth (66.33 ± 24.15 μm) and the measured ablation depth at the thinnest corneal location (67.04 ± 30.94 μm), the corneal apex (67.52 ± 31.22 μm), or the pupil center (67.73 ± 31.48 μm). Bland-Altman plots revealed moderate agreement for measurements at the thinnest point (95% limits of agreement [LoA]: -25.13 to 23.70 μm), corneal apex (95% LoA: -24.70 to 22.33 μm), and pupil center (95% LoA: -25.30 to 22.51 μm), with a proportional bias between the average ablation depth and DAD. The predicted ablation depth was overestimated in eyes with lower correction and underestimated in eyes with higher correction.
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