Three-Year Follow-Up of Laser In Situ Keratomileusis Treatments for Myopia: Multi-Center Cohort Study in Korean Population

Abstract

This multi-center cohort study included 3401 myopic laser in situ keratomileusis (LASIK) procedures conducted in 1756 myopia patients between 2002 and 2005. Pre- and postoperative uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and manifest refraction spherical equivalent (SE) were recorded. Factors predicting low postoperative efficacy (defined as a postoperative UCVA < 0.5) were identified using univariate and multivariate logistic regression analysis. Compared with 1 month postoperatively, logMAR UCVA at 3 months postoperatively was significantly decreased (p = 0.002) and that at 2 and 3 years was significantly increased (p < 0.001). LogMAR BCVA at 2 years postoperatively was significantly decreased compared with 1 month postoperatively (p = 0.008). Over the 3-year postoperative period, overall refractive predictability within ±1.00 D and ±0.50 D ranged from 69.0% to 86.2% and from 43.3% to 67.8%, respectively. This also decreased from 1 month to 6 months postoperatively (p < 0.005). Multivariate logistic regression analysis using generalized estimating equations, revealed that higher preoperative SE (odds ratio [OR], 2.58 and 7.23; p < 0.001) and lower preoperative BCVA (OR, 2.44; p = 0.003) were predictive of a low postoperative efficacy. In summary, myopic LASIK can be effective and safe with a high refractive predictability in a Korean population, but myopic regression occurs over time. Higher preoperative SE and lower preoperative BCVA are predictive of a low postoperative efficacy.

Keywords: efficacy; laser in situ keratomileusis; safety.

Figure 1

Overall incidence of postoperative uncorrected visual acuity ≥20/40, ≥20/30, and ≥20/20. ***, ** and *; †† and †; ‡‡ and ‡ indicate significant differences between these time points (all p < 0.005).

Figure 2

Distribution of postoperative spherical equivalents at 3 months and 3 years postoperatively (A) and percentage of eyes within ± 0.50 and ± 1.00 D emmetropia (in terms of spherical equivalent) at the indicated postoperative periods (B). ***, ** and *; †††, †† and † indicate significant differences between these time points (all p < 0.005). SE = spherical equivalent.

Figure 3

Comparison of pre- and postoperative uncorrected visual acuity according to the degree of myopia. *: significant difference among the three myopia groups (p < 0.050); ‡: significant difference between the low and moderate myopia groups, and between the low and high myopia groups (p < 0.050). UCVA = uncorrected visual acuity.

Figure 4

Incidence of uncorrected visual acuity of ≥20/40 (A), ≥20/30 (B), and ≥20/20 (C) according to the degree of myopia. *: significant difference among the three myopia groups (p < 0.010). UCVA = uncorrected visual acuity.

Figure 5

Comparison of best corrected visual acuity and efficacy index according to the degree of myopia. (A) BCVA. (B) efficacy index. *: significant difference among the three myopia groups (p < 0.050). †: significant difference between the low and moderate myopia groups (p < 0.050). ‡: significant difference between the low and moderate myopia groups, and between the low and high myopia groups (p < 0.050). BCVA = best corrected visual acuity.

Figure 6

Refractive predictability assessed as a percentage of eyes within ±0.50 and ±1.00 diopters (D) of the postoperative spherical equivalent. These are separately shown as the percentage of eyes within ±0.50 D in the low, moderate, and high myopia groups (A) and as the percentage of eyes within ±1.00 D in these same three groups (B). *: significant difference among the three myopia groups (p < 0.010). †: significant difference between the low and moderate myopia groups (p < 0.050).