Patients have better spherical equivalent outcomes with PRK, less discomfort with SMILE
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Key takeaways:
- In a study, PRK yielded better results than SMILE in spherical equivalent and cylinder correction.
- Patient-reported discomfort and vision were worse with PRK at 1 month but equal to SMILE at 18 months.
A study comparing PRK and SMILE in eyes with myopic astigmatism showed better results in spherical equivalent and cylinder correction with PRK but less discomfort and faster visual recovery with SMILE.
Forty-three patients were treated with PRK with mitomycin C in one eye and SMILE in the contralateral eye. Spherical equivalent was between –1 D and –8 D, and refractive astigmatism was 4.5 D or less.
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PRK wavefront-optimized ablation was performed using the WaveLight EX500 laser (Alcon) after mechanical removal of the epithelium, and the VisuMax femtosecond laser system (Carl Zeiss Meditec) was used for SMILE.
There was no statistically significant difference in uncorrected and corrected distance visual acuity between the two groups during the 18-month follow-up period, and 91% of eyes in the PRK group vs. 84% of eyes in the SMILE group achieved uncorrected distance visual acuity of 20/20 or better. Safety was also comparable. However, eyes treated with PRK had a significantly lower residual spherical equivalent at 3 months and 18 months. In the PRK group, 98% of eyes were within ±0.5 D of intended correction and 100% were within ±1 D at 18 months. In the SMILE group, the rates were 86% and 98%.
In the PRK group, 95% of eyes had residual astigmatism of 0.5 D or less compared with 81% in the SMILE group. In both groups, 100% of patients had residual astigmatism of less than 1 D. For higher astigmatism, linear regression of target induced astigmatism vs. surgically induced astigmatism showed a pattern toward overcorrection with PRK and undercorrection with SMILE. The angle of error was higher in the SMILE group, with 42% of eyes having more than 5° of error as compared with 19% in the PRK group.
At the 1-month visit, patients reported more foreign body sensation and worse vision in the PRK eye. However, equal outcomes were reported for the two eyes at 18 months.
“Considering the long-term data presented here, both PRK and SMILE proved to be safe and effective strategies for the treatment of myopia with comparative clinical results,” the authors wrote.
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