Redistribution of the corneal epithelium after overnight wear of orthokeratology contact lenses for myopia reduction

Abstract

Background: To investigate changes in the corneal thickness profile in juvenile myopia after overnight wear of orthokeratology lenses (OK). Methods: A total of 53 juveniles (53 right eyes) successfully wore OK between January 2016 and July 2017 and they were reviewed one day, one week and one month after first wearing it. Epithelial and corneal data were obtained by optical coherence tomography (OCT). Changes in uncorrected visual acuity, refractive error, corneal refractive power, and epithelial and corneal thickness were analyzed before and after wear of OK. Results: The corneal epithelium was reshaped after 1 day of OK; the myopia degree was reduced, and uncorrected visual acuity reached 0 logMAR at 1 week. The central (2 mm) average epithelial thickness was 52.04 ± 2.35 μm, 49.25 ± 2.67 μm, 45.91 ± 2.80 μm, and 47.53 ± 3.44 μm before and after 1 day, 1 week, and 1 month of OK, respectively (t = 4.497, 9.741, and 7.340, respectively, P < 0.001). The central epithelium was thinnest at 1 week, when the average thinning of 6.13 ± 1.67 μm accounted for approximately 11.78 % ± 3.21 % of the total epithelium thickness at baseline. The epithelial thickness of the reverse curve zone was 51.83 ± 2.49 μm, 57.62 ± 3.01 μm, 59.43 ± 3.19 μm, and 60.22 ± 2.75 μm before and after 1 day, 1 week, and 1 month of OK, respectively, showing a significant increase over time (t=-4.752,-6.208, and-6.848, respectively, P < 0.001). Conclusion: In the early stage of OK, the corneal epithelium was redistributed very quickly. The central epithelium became thin, while the epithelium of the reverse curve zone correspondingly thickened. Effectively reduced the refractive power of the cornea equivalent to the effect of adding a concave spectacle lens, which ensures uncorrected vision after removal of the lenses.

Corneal thickness changes in myopic children during and after short‐term orthokeratology lens wear

“…Results on the changes in thickness at the central cornea were also in agreement with previous studies using AS-OCT, which reported significant CCT and CET reduction after commencement of ortho-k lens wear in children. [12][13][14] The magnitude of observed reduction in CET was also comparable. The current study showed that increasing the compression factor by 1.00 D could induce a significantly higher amount of central epithelial thinning (reduction of CET of 6.64 AE 3.29 lm in CCF eyes and 7.98 AE 3.06 lm in ICF eyes).…”

“…Anterior segment OCT has been used to investigate corneal changes after ortho-k lens wear in children. [12][13][14] These studies confirmed that ortho-k lens wear induces central corneal thinning, but conflicting results were found for peripheral corneal changes. Two studies 12,13 reported significant thickening in the peripheral (5-6 mm) cornea, but one observed insignificant changes.…”

“…The current study showed that increasing the compression factor by 1.00 D could induce a significantly higher amount of central epithelial thinning (reduction of CET of 6.64 AE 3.29 lm in CCF eyes and 7.98 AE 3.06 lm in ICF eyes). Qian et al 12 reported CET thinning of 6.9 to 5.5 lm after short-term (4.7 AE 3.9 days) and long-term (278.8 AE 280 days) ortho-k lens wear. Kim et al 13 investigated the data from a retrospective cohort and reported thinning in CET of 7.62 AE 3.62 lm in children, who had worn ortho-k lens for 2-4 weeks.…”

“…Qian et al and Kim et al recruited subjects who had been wearing lenses for between 3 weeks and 3 years and two to 40 weeks, respectively. 12,13 Hence the difference in peripheral thickness changes could be due to differences in ortho-k lens wearing duration. The current study as well as that of Zhang et al, 14 showed no significant thickening at the peripheral cornea, when subjects were required to wear ortho-k lenses for 1 month.…”

Orthokeratology lens-related Acanthamoeba keratitis: case report and analytical review

“…33,34 Different from the regular alignment fit of the RGP lens, the shape of the OK lens and the inherent tight bending between the lens and cornea can induce central corneal epithelial thinning and surface cell damage, which predisposes the cornea to an increased risk of infection. 35,36 On the basis of different designs of the same material, Wei et al 37 suggested that the OK lens produces a higher risk of microbial keratitis than the alignment fit RGP lens with overnight wearing because the OK lens resulted in greater cornea binding for pathogens in their study. Choo et al 38 stated that tear pooling under the reverse curve of the OK lens created higher colonization rates than the alignment fit lens, under which the tear fluid was evenly distributed.…”