Treatment of corneal astigmatism with the new small-incision lenticule extraction (SMILE) laser technique: Is treatment of high degree astigmatism equally accurate, stable and safe as treatment of low degree astigmatism?

摘要

Field: Ophthalmology Introduction: SMILE has proven effective in treatment of myopia and low degrees of astigmatism (less than 2 dioptres (D)), but there are no studies on treatment of high degrees of astigmatism (2 or more D). The aim of this study was to compare results after SMILE treatment for low or high degrees of astigmatism concerning accuracy, stability, and safety. Methods: Retrospective study of 1017 eyes treated with SMILE for myopia with low astigmatism or myopia with high astigmatism from 2011-2013 at the Department of Ophthalmology, Odense University Hospital, Denmark. Inclusion criteria were: Best spectacle-corrected visual acuity (BSCVA) of 20/25 or better on Snellen chart, and no other ocular condition than myopia with or without astigmatism. Results: In total 660 eyes completed the 3 months follow-up examination, in which 536 eyes had pre-operatively low astigmatism (mean astigmatism -0.59±0.52 D, range: 0.00 to -1.75) and 124 eyes had pre-operatively high astigmatism (mean astigmatism -3.09±0.77 D, range: -2.00 to -5.75). Accuracy: 88% of eyes with low astigmatism and 65% of eyes with high astigmatism (P=0.06) were within ±0.5 D of attempted post-operative astigmatism, whilst 98% of eyes with low astigmatism and 95% of eyes with high astigmatism (P=0.89) were within ±1.0 D. Stability: In total 38% of eyes with low astigmatism and 32% of eyes with high astigmatism (P=0.49) changed ≥0.5 D in refraction from one day to three months after surgery. Safety: Three eyes (0.6%) treated for low astigmatism and four eyes (3.2%) treated for high astigmatism (P=0.02) had lost two or more lines of BSCVA after three months. Conclusion: This study is the first of its kind, and our results indicate that SMILE treatment of high degree astigmatism is equally accurate and stable as treatment of low degree astigmatism. More eyes treated for high degree astigmatism lose two or more lines of BSCVA up to three months after surgery. Keywords Refractive surgery, astigmatism, SMILE