Long-term follow-up of changes in ocular biometric parameters in orthokeratology lens wearers with relatively large-scale axial length reduction

Abstract

Background To investigate ocular biological characteristics for myopic children with axial length (AL) reduction during orthokeratology (Ortho-K) treatment and provide clinical clues for better myopia control effects. Methods Changes in ocular parameters and treatment zone (TZ) in 75 subjects who completed one-year Ortho-K treatment were retrospectively reviewed. The subjects were divided into two groups according to one-year AL change: the AL reduction group (n = 37) and the AL elongation group (n = 38). Univariate and multivariate regression analyses were performed to determine the association between TZ, ocular parameters, and AL change. Results There was no significant difference in baseline between the two groups (all P > 0.05). After one year of Ortho-K treatment, compared with those in the AL elongation group, children in the AL reduction group had a decreased anterior chamber depth (ACD) (P < 0.001), thickened crystalline lens thickness (CLT) (P = 0.002), thinned vitreous chamber depth (VCD) (P < 0.001) and smaller TZ (P = 0.03), but no difference in central corneal thickness (CCT) and pupil diameter (PD). In the multivariable analyses, AL reduction was negatively associated with baseline age (beta: − 0.048; 95% CI: − 0.083 to − 0.013; P = 0.009) and positively associated with the TZ (beta: 0.024; 95% CI: 0.009 to 0.040; P = 0.003). Conclusions In AL reduction eyes, thickened CLT, decreased ACD and thinned VCD were observed during Ortho-K treatment, which could be suggested as indicators for better myopia control effects in the clinic. Older baseline age and smaller TZ wearing Ortho-K were also associated with AL change. Thickened CLT may be a result of compensation for AL-reduction eyes.

In vivo assessment of human corneal epithelial cells in orthokeratology lens wearers: A pilot study

“…Although several studies have reported a reduced rate of axial elongation with ortho-k, suggesting its potential for controlling myopia progression, especially in children, 9,14–17 a better understanding of the cellular mechanism underlying ortho-k treatment and its effect on cornea anatomy and physiology will be a critical step forward to optimize this technology and establish its clinical benefits, especially in the context of slowing myopia progression. Polarization-dependent optical coherence microscopy offers a unique opportunity to achieve this goal.…”

“…Furthermore, the reduced rate of axial length elongation at a younger age may improve visual experiences and reduce the risks of developing further into vision complications at later ages 13 . Unlike single-vision spectacles, ortho-k correction has been reported to reduce peripheral hyperopic defocus, which has been identified as the key stimulus to axial elongation and myopia progression 9,14–17 . Animal studies reported that inducing peripheral hyperopic defocus increases the rate of axial length growth, whereas peripheral myopic defocus reduces the rate of axial length growth, slowing myopia progression 18–22 .…”

“…Animal studies reported that inducing peripheral hyperopic defocus increases the rate of axial length growth, whereas peripheral myopic defocus reduces the rate of axial length growth, slowing myopia progression 18–22 . Similarly, several clinical studies reported that ortho-k treatment reduces peripheral hyperopic defocus, thus slowing the rate of axial length elongation compared with spectacle correction 14,17,22–24 . It has been hypothesized that the regional change in corneal epithelial thickness induced by ortho-k, especially the thinning of the central epithelium and the thickening of the midperipheral epithelium, was the primary factor contributing to the effect of ortho-k 9,14,16,17,23,25–32 .…”

“…Similarly, several clinical studies reported that ortho-k treatment reduces peripheral hyperopic defocus, thus slowing the rate of axial length elongation compared with spectacle correction 14,17,22–24 . It has been hypothesized that the regional change in corneal epithelial thickness induced by ortho-k, especially the thinning of the central epithelium and the thickening of the midperipheral epithelium, was the primary factor contributing to the effect of ortho-k 9,14,16,17,23,25–32 . However, the exact morphological changes in the epithelial layers that govern ortho-k treatment are still not well understood 11,33 …”

Sleep Quality is Associated with Axial Length Elongation in Myopic Children Receiving Orthokeratology: A Retrospective Study

“…A 2-year follow-up study revealed that corneal biomechanics was associated with axial length (AL) progression in children wearing orthok. 10 In addition, multiple studies have reported that age, ortho-k wearing time, and baseline refractive error level were correlated with subsequent myopia control and axial elongation in patients wearing ortho-k. [11][12][13] Furthermore, a previous report demonstrated that poor sleep quality was closely related to refractive errors in children and a potential target for myopia progression; 14 however, the debate continues on the relationship between sleep quality and the occurrence or development of myopia. Till recently, the potential role of sleep quality on the efficacy of ortho-k treatment remained unclear.…”