Effect of orthokeratology in patients with myopic regression after refractive surgery

To evaluate the clinical effect of orthokeratology (ortho-K) lenses and to introduce the fitting steps of ortho-K lens for myopic regression after keratorefractive surgery.

Twenty-one eyes from 12 patients with myopic regression after keratorefractive surgery were fitted with ortho-K lenses and followed up for 12.11±3.68 months. The mean K value of the peripheral cornea was used to speculate preoperative central corneal K value, estimated K. After dispensing the lenses according to estimated K, biomicroscopic examination including fluorescein staining and over-refraction were performed to determine the final K and final lens power.

LogMAR uncorrected visual acuity was 0.48±0.39 before and 0.00±0.00 after wearing ortho-K lenses (p<0.001). Pre-fitted refractive error was -1.87±1.05 diopters (D) in myopia, 0.54±0.42 D in astigmatism, and spherical equivalent of -2.14±1.01 D. At the final visit myopia level and spherical equivalent significantly decreased to -0.73±0.84 D (p<0.001) and -1.01±0.87 D (p<0.001), respectively. Estimated K was 8.07±0.36 mm, and final K used for ortho-K prescription was 8.19±0.30 mm. Final K significantly correlated with K value of pre-fitted peripheral cornea (r=0.737, p<0.001) and estimated K (r=0.721, p<0.001), respectively. There was no correlation between pre-fitted degree of myopia and the Final lens power (r=0.429, p=0.053).

Ortho-K lenses may be an effective solution for patients with myopic regression following keratorefractive surgery. Estimated K value can be used as reference value in ortho-K prescription.