Poster Abstract

Purpose
To raise awareness of the influence of high order aberrations (HOAs) on astigmatism power and axis. In addition, to compare outcomes of vector-compensation refraction (VR), topography modified refraction (TMR) and clinical refraction (CR) in topography-guided LASIK.
Methods
Retrospective. A total of 89 eyes (45 patients) in consecutive cases underwent a topography-guided LASIK procedure for myopic and astigmatic correction. Post-operative residual astigmatism power and axis were measured with wavefront device. Vector analysis was used to evaluate ought-to-be treated astigmatism through the corresponding corrected and residual astigmatic values. Then three different strategies were applied for simulated retreatments: Strategy A, B and C was assigned to VR (open access), TMR and CR, respectively. The theory of VR was to consider both clinical refraction and refraction affected by HOAs, and apply vector analysis to finalize correction on astigmatic power and axis.
Results
Preoperative clinical astigmatism was -2.03D ± 1.25D, ranged from -6.00D to 0.00D. Strategy A, Strategy B and Strategy C respectively: postoperative cylinder was -0.39D ± 0.22D, -0.74D ± 0.45D and -0.50D ± 0.24D (F=26.505, P=0.000), and differences between each two groups were statistically significant (Strategy A vs. B: P=0.000, Strategy A vs. C: P=0.025 and Strategy B vs. C: P=0.000). Percentage of postoperative cylinder within 0.50D was 66.29%, 33.71% and 51.69% (2=18.97, P=0.000), and differences between each two groups were statistically significant (Strategy A vs. B: P=0.00, Strategy A vs. C: P=0.048 and Strategy B vs. C: P=0.015).
Conclusion
Vector compensation refraction may offer superior outcomes in topography-guided myopic LASIK. These findings may improve the current clinical paradigm of the optimal subjective refraction utilized in laser vision correction.