Effect of Toric Orthokeratology Lenses on Patients with More Than 1.5 Diopter of Corneal Astigmatism

ABSTRACT

PURPOSE: To report the effect of toric orthokeratology lenses on myopic patients who have more than 1.5 diopter (D) of corneal astigmatism. METHODS: Seventeen patients (24 eyes) who wore toric orthokeratology lenses for more than 6 months were recruited for this study. The uncorrected visual acuity (UCVA), refractive error and keratometric changes including eccentricity before and after wearing lenses were compared. The correlations between corneal astigmatism as well as refractive astigmatism and lens toricity and between corneal astigmatism and improvement of UCVA after lens fitting were assessed. RESULTS: After wearing lenses, UCVA (log MAR) was significantly improved from 0.93 +/- 0.13 to 0.09 +/- 0.07 (p < 0.001). Myopia changed from -4.53 +/- 1.55 D to -0.67 +/- 0.80 D (p < 0.001), refractive astigmatism from -1.48 +/- 0.71 D to -0.99 +/- 0.72 (p = 0.008) and spherical equivalent from -5.27 +/- 1.56 D to -1.12 +/- 0.92 D (p < 0.001). Simulated K (Sim K) tended to be more flat (p < 0.001) and the eccentricity was significantly decreased from 0.45 +/- 0.08 to -0.69 +/- 0.45 (p < 0.001), but corneal astigmatism was not significantly changed from 2.05 +/- 0.41 D to 2.01 +/- 0.98 D (p = 0.803). Correlation between corneal astigmatism and lens toricity was statistically significant (r = 0.526, p = 0.012) but not between refractive astigmatism and lens toricity (r = 0.218, p = 0.329). The amount of corneal astigmatism was not correlated with the improvement of uncorrected visual acuity after lens fitting (r = 0.1804, p = 0.399). CONCLUSIONS: Toric orthokeratology lenses might be an effective treatment in patients with corneal astigmatism who cannot be fitted with spherical orthokeratology lenses. Lens toricity was correlated with corneal astigmatism and the amount of corneal astigmatism did not affect the improvement of uncorrected visual acuity after lens fitting.