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

Abstract

Purpose: To evaluate thickness changes in the central and mid-peripheral cornea (CCT and mPCT), corneal epithelium (CET and mPET) and stroma (CST and mPST) of myopic children during and after short-term orthokeratology (ortho-k) lens wear, with conventional (CCF, 0.75 D) and increased compression factors (ICF, 1.75 D). Methods: This was a self-controlled case series study. Subjects wore a CCF lens in one eye and an ICF lens in the other. Anterior segment optical coherence tomography images were captured weekly for 1 month during lens wear and for 2 weeks after discontinuing lens wear. CCT and CET (central 3-mm cornea) and mPCT and mPET (within a 4-6 mm diameter annulus) were measured. Stromal thickness (ST) was determined by subtracting epithelium thickness (ET) from corneal thickness (CT). The repeatability of the analytical software was also investigated on age-matched spectacle-wearing subjects (n = 98). Results: Excluding three outliers (>3 S.D.s), the coefficient of repeatability and intraclass correlation coefficients of 98 spectacle-wearing subjects ranged from 2.63 to 4.64 lm and from 0.90 to 0.99, respectively. For the weeklychange study, CCT and CET in both eyes were significantly thinner after lens wear (p < 0.001) and CET thinning in the ICF eyes were significantly higher (p < 0.02). CCT changes were mainly contributed by CET. CST, mPCT, mPET and mPST changes were not significant (p > 0.20) in either eye. CT (all sublayers) rebounded to baseline values 2 weeks after discontinuing lens wear (0.99 > p > 0.12). Conclusions: Significant reductions in CT and ET, but not ST, were observed within 1 month of ortho-k lens wear. Wearing ICF lenses resulted in a higher reduction in CET. Corneal thickness changes were reversible after discontinuing lens wear.

The Biomechanical Response of the Cornea in Orthokeratology

“…However, in the normal range, the corneal thickness is the factor that has the least influence on the corneal stress response among all the factors. After wearing ortho-k lenses, the corneal thickness has a certain amount of thinning ( Wan et al, 2021 ). However, a large number of studies have found that the changes of corneal thickness are mainly confined to the corneal epithelium ( Kim et al, 2018 ; Zhang J. et al, 2020 ; Zhou et al, 2020a ; b ).…”

Changes in optical biometry throughout childhood and adolescence for orthokeratology patients

“…Recent studies have also shown a reduction in CCT after Ortho-K initiation in as little as 1 week unrelated to age. [29,30] This reduction has been demonstrated in prior studies to be con ned to the corneal epithelial layer. [31,32] There is limited research on corneal keratometry changes post Ortho-K. Average difference in lens thickness, in mm, between the pre-Ortho-K intervention and a second measurement taken approximately 1 year after Ortho-K intervention strati ed by age at rst measurement.…”

Modeling and Prediction of the Immediate and Short-Term Effect of Myopic Orthokeratology

“…The largest thinning was achieved 1 week after starting the treatment (8.1760.59 mm), being this outcome in agreement with those reported by other authors. [14][15][16] In particular, Quian et al 14 published an OCT-based pachymetry map of the corneal epithelium that showed a thinning of the central and paracentral area of the cornea after using OK for 2 weeks. Zhang et al 15 reported changes in central epithelium thickness (CET) from the first night, showing a fast change from 5 to 13 mm.…”