Abstract
Abstract: :
Purpose: To examine existing FDA data on LASIK for myopia and myopic astigmatism for trends in outcomes related to changes/improvements in laser design. Methods: The Summary of Safety and Efficacy Data documents for each of the 11 lasers approved by the FDA for LASIK for myopia or myopic astigmatism were downloaded from the FDA webpage. The proportion of patients with various visual acuity outcomes, refractive error outcomes, and symptoms were extracted from the summary documents and entered into a database. The Cochran–Armitage Test for Trend was used to determine if improvements in outcomes have occurred with the development of new laser types, comparing broad beam lasers, scanning lasers, scanning lasers with eye trackers, and wavefront–guided lasers for all eyes tested and also for only low myopes. The criterion for statistical significance was adjusted to p < 0.0001 for multiple comparisons. Results: For analyses including all eyes tested, there was a statistically significant increase in the percentage of patients across laser type for each of the following outcome measures: percentage of patients with uncorrected visual acuity (UCVA) of 20/20 or better (Z = 20.76, p < 0.0001), UCVA of 20/40 or better (Z = 6.39, p < 0.0001), results within 0.50 D of intended correction (Z = 11.31, p < 0.0001), results within 1.00 D of intended correction (Z = 10.55, p < 0.0001), and results within 2.00 D of intended correction (Z = 4.21, p < 0.0001). Conversely, there was no difference across laser types in the percentage of patients who experience dry eye symptoms (Z = –1.56, p = 0.12). Results for analyses including only low myopes were similar to those for analyses including all eyes. Conclusions: Based on trend tests with proportions, there appears to be a trend for improved outcomes with changes in laser technology. Future studies should determine if these results are also applicable to high myopes. Given that changes in patient selection criteria also occurred over time, future studies should determine if the results are similar when comparisons are made among patients who were randomly assigned to different laser types.
Keywords: refractive surgery: LASIK • refractive surgery: comparative studies • refractive surgery: optical quality