Long-term Effect of Orthokeratology Lenses on Axial Length Elongation in Myopia: 2-3 Years Follow-up Study

ABSTRACT

Purpose@#To evaluate the effect of orthokeratology lenses on axial length elongation and associated factors in eyes treated withorthokeratology lenses for 2-3 years. @*Methods@#Thirty-four eyes of 20 patients treated with orthokeratology lenses for more than 22 months were enrolled into the orthokeratology(OK) group. Uncorrected distant visual acuity, spherical equivalent, axial length, and high-order aberrations of theanterior cornea at baseline and during the follow-up period were analyzed retrospectively. Spectacle-wearing patients matchedwith the OK group patients by sex, age, refractive error and follow-up period were selected as a control group. To adjust for follow-upperiod differences, the 24-month conversion axial length changes were calculated and compared between the two groups. @*Results@#The 24-month conversion mean axial length change showed significant differences (0.50 ± 0.23 mm in the OK groupversus 1.00 ± 0.28 mm in the control group; p< 0.001). For the OK group, the age at starting OK lens (r = -0.572, p= 0.001)showed statistically significant correlation with axial elongation. The anterior corneal spherical aberrations (SA) and coma with 6mm pupil at last follow-up (SA r = 0.543, p= 0.001; coma r = 0.420, p= 0.017) and the total SA and total coma changes (ㅿSAr = 0.518, p= 0.002; ㅿcoma r = 0.420, p= 0.017) also showed a statistically significant correlation. The initial age and axiallength, the anterior corneal SA and ㅿSA values were identified as factors significantly correlated with axial length elongation bymultiple regression analysis. @*Conclusions@#The OK lens effectively suppressed axial length elongation during a 2-3 years treatment period. However, whenthe age of starting OK lens was younger and the anterior corneal spherical aberration during the follow-up period was larger, therisk of axial elongation was higher.