Ray Trace Lasik In Patients With Asymmetric Astigmatism: A Retrospective Case Series

To evaluate clinical outcomes, including changes in corneal and ocular higher order aberrations (HOAs), following the treatment of asymmetric astigmatism using ray-tracing-guided LASIK.

Single centre ophthalmology practice

Ray trace guided LASIK creates a personalised ablation profile by constructing an individualised eye model incorporating corneal tomography, pachymetry, anterior chamber depth, axial length and wavefront measurements. Real time pupil tracking is used during laser ablation. This retrospective case series included five eyes of five patients with preoperative asymmetric astigmatism who underwent ray trace guided LASIK. Preoperatively, 4 eyes showed vertical and 1 eye showed horizontal asymmetric astigmatism. Primary outcomes included subjective spherical equivalent (SEQ), corrected distance visual acuity (CDVA), corneal HOA and wavefront ocular HOA measured preoperatively and 3 months post operatively.

Post operatively, mean subjective SEQ improved from -2.52±2.38D (mean±SD) (range: -5.5 to -0.125D) to 0.03±0.35D (range: -0.25 to 0.63D). No eyes lost lines of CDVA. Ocular and corneal spherical aberration significantly decreased (mean±SEM) (0.17±0.04µm to 0.04±0.05µm, p=0.02 and 0.67±0.13µm to 0.53±0.04µm, p=0.04 respectively). 4 eyes with vertical asymmetric astigmatism showed insignificant improvement in ocular vertical coma and significant improvement in corneal vertical coma (mean±SEM) (0.24±0.07µm to 0.15±0.05µm, p=0.15 and 0.32±0.17µm to 0.05±0.04µm, p<0.05 respectively). 1 eye with horizontal asymmetric astigmatism showed a magnitude increase in ocular horizontal coma of 0.15µm and improvement in corneal horizontal coma of 0.11µm. 

Ray trace LASIK is an effective and safe treatment for eyes with horizontal and vertical asymmetric astigmatism and should be considered for unusual corneas.