Femtosecond-Laser-Assisted Liquid-Interface vs Vacuum-Trephine Keratoplasty: A Comparison of 2 Different Techniques - Retrospective Data Analysis.

Purpose: To compare postoperative astigmatism and visual acuity (VA) outcomes in patients undergoing penetrating keratoplasty (PK) using a liquid-interface femtosecond laser (LI-fs) trephination and a conventional vacuum-trephine (VT) technique.

Methods: Our single-center, retrospective data analysis included 121 eyes (121 patients) treated between April 2014 and November 2022. Patients received PK either with a LI-fs or a VT system. Pre- and postoperative topography (K-values), refraction (cylinder) and visual acuity (VA) were measured up to 18 months after surgery. Data were analyzed by descriptive statistics, ANCOVA, and paired t-tests within each group.

Results: Preoperative and postoperative astigmatism were similar between the two techniques (LI-fs: 5.4 ± 3.4 D pre-OP vs 6.7 ± 4.2 D post-OP; VT group: 5.8 ± 4.8 D vs 6.7 ± 3.8D). An ANCOVA adjusting for baseline astigmatism (=∆K in topography imaging) revealed no statistically significant difference between groups (estimate [95% CI]: -0.79 [-2.73; 1.15], p = 0.42). Within-group changes in astigmatism were also not significant. For VA, a paired -test showed a significant increase of post-OP VA in the VT group (mean change 0.25 [0.15; 0.34], p < 0.0001), while the smaller LI-fs group showed no significant change (mean 0.16 [-0.11; 0.44], p = 0.22).

Conclusion: Despite the characteristics of LI-fs in maintaining corneal curvature, LI-fs and conventional VT generated comparable outcomes in terms of post-OP astigmatism. The results underscore the need for further research with larger cohorts to clarify any potential advantages of the LI-fs in reducing surgically-induced astigmatism.