Introduction: To investigate the effects of an orthokeratology lens on the tear film and tarsal glands and myopia control in children with unilateral myopia using an intelligent analysis model.
Discussion: Wearing orthokeratology lenses at night can effectively control myopia progression in children with unilateral myopia. However, long-term use of these lenses may lead to meibomian gland deformation and impact tear film function, and the extent of deformation may vary at different positions in the central region.
Volume 11 - 2023 | <a class="ArticleLayoutHeader__info__doi" href="https://doi.org/10.3389/fcell.2023.1197262">https://doi.org/10.3389/fcell.2023.1197262</a>
This article is part of the Research TopicArtificial Intelligence Applications in Chronic Ocular Diseases<a class="Link Link--linkType Link--maincolor Link--medium Link--icon Link--chevronRight Link--right" aria-label="View all 31 articles" href="https://www.frontiersin.org/research-topics/46069/artificial-intelligence-applications-in-chronic-ocular-diseases/magazine" target="_self" data-event="customLink-linkType-a_viewAll31Articles">View all 31 articles</a>
Introduction: To investigate the effects of an orthokeratology lens on the tear film and tarsal glands and myopia control in children with unilateral myopia using an intelligent analysis model
Methods: We retrospectively reviewed the medical records from November 2020 to November 2022 of 68 pediatric patients with unilateral myopia in Fujian Provincial Hospital who had been wearing an orthokeratology lens for more than 1&#x000a0;year
The 68 myopic eyes were included in the treatment group
untreated contralateral eyes were included in the control group
Tear film break-up times (TBUTs) were compared between the two groups at various intervals
and an intelligent analysis model was used to compare the deformation coefficients of 10 meibomian glands in the central area and the different positions of the glands in the two groups after 12&#x000a0;months of treatment
Changes in axial length and equivalent spherical power were also compared between the groups before and after 12&#x000a0;months of treatment
TBUTs differed significantly between 1 and 12&#x000a0;months after treatment
although no significant differences from baseline were observed at 3 or 6&#x000a0;months
No significant differences in TBUTs were observed at any time point in the control group
significant between-group differences were observed for glands 2
and 10 (numbered from the temporal to nasal regions)
The treatment group also exhibited significant differences in deformation coefficients at different detection positions in the central region
with glands 5 and 6 exhibiting the highest deformation coefficients
Increases in axial length and equivalent spherical power were significantly greater in the control group than in the treatment group after 12&#x000a0;months of treatment
Discussion: Wearing orthokeratology lenses at night can effectively control myopia progression in children with unilateral myopia
long-term use of these lenses may lead to meibomian gland deformation and impact tear film function
and the extent of deformation may vary at different positions in the central region
technological advancements have introduced a variety of electronic products and children&#x02019;s toys that are viewed within a close range and have become ubiquitous in daily life
The childhood developmental period is a critical window for both cognitive and physical growth
Increased emphasis on educational attainment has resulted in a high frequency of close-range eye behaviors (e.g.
When coupled with improper reading and writing postures
this can lead both eyes to develop different degrees of myopia during eye development
one eye may develop myopia earlier than the other
Children with unilateral myopia present with overload of the myopic eye when viewing near objects
which can aggravate the progression of myopia and lead to symptoms of ocular fatigue due to decreased coordination between the eyes
If the difference in the refractive error between the two eyes is greater than 2.5 D
and children can find it difficult to adapt to wearing frame glasses
long-term use of an orthokeratology lens may exert detrimental effects on the tear film and tarsal glands via mechanical irritation or hypoxic interference
To address this gap in knowledge and determine the effectiveness of myopia control
the present retrospective study was designed to investigate the effects of orthokeratology lenses on the tear film and tarsal glands in children with unilateral myopia
we analyzed complete data of pediatric patients treated at our hospital who had been wearing an orthokeratology lens in one eye continuously for more than 12&#x000a0;months using an intelligent analysis model
We reviewed the medical records from November 2020 to November 2022 of 68 pediatric patients with unilateral myopia treated in the Department of Ophthalmology of Fujian Provincial Hospital
The myopic eyes of patients treated using an orthokeratology lens were included in the treatment group (68 eyes)
in which the mean spherical equivalent was &#x02212;1.92 &#x000b1; 1.21 D
untreated contralateral eyes were included in the control group (68 eyes)
in which the mean spherical equivalent was &#x0002b;1.06 &#x000b1; 0.68 D
The inclusion criteria were as follows: a) age of 8&#x02013;14&#x000a0;years
b) more than 1&#x000a0;year of complete data for review
c) diagnosis of unilateral myopia with a spherical equivalent of &#x02212;1.00 to 6.00 D in the myopic eye
d) best corrected visual acuity &#x02265;5.0 in both eyes
and e) normal intraocular pressure and fundus in both eyes
The exclusion criteria were as follows: a) organic eye disease; b) corneal diseases
moderate or severe allergic conjunctivitis
or keratoconus; c) poor compliance and/or inability to be followed up according to medical advice; d) combined use of other myopia interventions
such as low-dose atropine and defocus lenses; and e) contraindications to orthokeratology lens use
The risks and potential complications of wearing the orthokeratology lens were explained in detail to the patients and guardians before treatment
The study was approved by the Ethics Committee (K2020-03-124) of the hospital
and the parents or guardians of the enrolled patients signed an informed consent form
All patients underwent appropriate eye examinations prior to enrolment and fitting
and infrared photography of the tarsal glands
Patients eligible for the orthokeratology lens were screened with reference to the inclusion criteria
A suitable trial orthokeratology lens was selected for try-on and evaluation based on the corneal diameter and corneal topography of each patient
the dynamic and static fit of the lens was evaluated
and the parameters of the trial lens were adjusted until the ideal fit was achieved
A lens with ideal fit was defined as a well-centered lens with 1&#x02013;2&#x000a0;mm of mobility when blinking
All patients were instructed by the same optometrist on the standard methods of lens removal
The minimum and maximum durations of nighttime lens wear were set to 8&#x000a0;h and 10 h
UNet&#x0002b;&#x0002b; was introduced to construct a tarsal gland segmentation model and provide a workflow for automatic gland segmentation, as shown in <a href="#F1">Figure 1</a>
We considered tarsal gland segmentation as a binary classification problem at each pixel of an image
Tarsal gland segmentation was divided into two stages (training and segmentation) and included the following three modules
The procedure for meibomian gland segmentation based on UNet&#x0002b;&#x0002b;
an automatic data augmentation strategy was introduced to randomly select N of 11 types of data augmentation methods (e.g.
following which the corresponding magnitude of transformation
we set N to 2 and the selection range for M to 1&#x02013;10 based on experimental findings
The data augmentation module used for this study did not require a manually designed data augmentation strategy
could provide adequate data samples for the gland segmentation model
and enhanced the generalizability of the model
The infrared images of the tarsal glands were grayscale images, which do not contain rich semantic information. Our preliminary analyses indicated that it would be inappropriate to use a complex network model. Proposed in 2015, the UNet model (<a href="#B9">Ronneberger et al., 2015</a>) was designed specifically for application in medical image segmentation
UNet uses hop connections to merge the superficial and deep semantic feature maps to overcome the information loss caused by subsampling
thereby significantly improving the accuracy of medical image segmentation
UNet&#x0002b;&#x0002b; is an improved version of UNet in which the hop connections have been redesigned to further reduce the semantic gap in merging the features between encoder and decoder
This module was used to introduce the UNet&#x0002b;&#x0002b; model as the main network for automatic gland segmentation
a small portion of the automatically segmented images can be processed again to capture missed areas or select additional areas using the editing tool in the software
the parameters of the gland model were analyzed
and the deformation coefficients of the glands (reflecting the degree of gland deformation) were automatically calculated
The deformation coefficient was calculated as follows:
The formula for calculating the deformation coefficient of the gland was established and improved upon based on the arc-string ratio model (<a href="#F2">Figure 2</a>)
pa refers to the length of the left side of the gland
pb refers to the length of the right side of the gland
wi refers to the diameter of the gland taken after each step
wavg refers to the average diameter of the gland
length (central) refers to the length of the central line
n refers to the number of diameters taken by the gland
and the deformation coefficients are dimensionless units
All enrolled patients underwent an eye examination before treatment (when the custom-made orthokeratology lens arrived)
which was considered the starting point of the observation period
and 12&#x000a0;months after initiating treatment
Indicators evaluated in this study included TBUT
as well as adverse reactions during the treatment period
The inferior conjunctival sacs of both eyes were lightly touched with a fluorescein sodium strip that had been moistened with saline
The patient was asked to blink three times to allow the cornea to make full contact with the fluorescein
and the corneal condition was observed under cobalt blue light with a slit lamp
the patient was advised not to blink until a black spot appeared on the cornea
The time taken for the first black spot to appear during the examination was recorded
and the measurement was repeated three times to obtain an average value
Changes in the morphology of each tarsal gland were analyzed using the intelligent model
the deformation coefficients of 10 glands in the central regions of the upper eyelids of both eyes were calculated after 12&#x000a0;months of treatment
Using the midline of the overall tarsal gland area of each patient&#x02019;s upper eyelid as the center
values were calculated for five glands extending towards the nasal and temporal sides
resulting in a total of 10 glands for analysis
The 10 glands were numbered such that the first tarsal gland at the temporal side was considered gland 1
while the first tarsal gland on the nasal side was considered gland 10
IOLMaster was used to examine axial length
and the measurement was repeated five times to obtain an average value
The patients were administered 1% compound tropicamide eye drops to fully paralyze the ciliary muscle
Treated eyes underwent optometry using an automatic computerized refractometer while the orthokeratology lens was in place
while control eyes underwent the same assessment on the naked eye
The measurement was repeated five times to obtain an average spherical equivalent value
Data were statistically analyzed using SPSS 22.0 software
Independent samples t-tests were used to compare the average values of the two groups at each time point
Paired t-tests were used to compare the average values of the same group at different time points
Paired samples t-tests were also used to evaluate the deformation coefficients of the 10 tarsal glands in the central region in the two groups after 12&#x000a0;months of treatment
A one-way analysis of variance (ANOVA) was used to evaluate the deformation coefficients of the tarsal glands at different examination locations in each of the two groups
The measurement data of both groups were expressed as mean &#x000b1; standard deviation (x &#x000b1; s)
whereas the count data were expressed as proportions (%)
A difference was considered statistically significant when p &#x0003c; 0.05
Data were retrospectively analyzed for 68 patients (30 boys, 38 girls; mean age: 11.12 &#x000b1; 0.76&#x000a0;years; age range: 8&#x02013;14&#x000a0;years). The characteristics of the included patients are summarized in <a href="#T1">Table 1</a>
In the treatment group, there were no statistically significant differences in TBUT from baseline at 3 or 6&#x000a0;months after treatment (p &#x0003e; 0.05). However, TBUTs differed significantly between 1 and 12&#x000a0;months after treatment (p &#x0003c; 0.05). No significant differences in TBUT from baseline were observed at any time point in the control group (p &#x0003e; 0.05) (<a href="#T2">Table 2</a>)
Comparison of tear film break-up time before and at 1
and 12&#x000a0;months after treatment initiation in the treatment and control groups
Significant between-group differences in deformation coefficients were observed for glands 2, 3, 4, 5, 6, 7, 8, and 10 in the central region (p &#x0003c; 0.05). In all cases, deformation coefficients were higher in the treatment group than in the control group (<a href="#T3">Table 3</a>)
Differences in gland deformation coefficients between the groups
Within the treatment group, significant differences in gland deformation coefficients were observed across different examination sites. Deformation coefficients for glands 5 and 6 were higher than those for glands 3 and 4, while deformation coefficients for glands 3 and 4 were higher than those for glands 1, 2, 8, 9, and 10 (<a href="#T4">Table 4</a>; <a href="#F3">Figure 3</a>)
Differences in gland deformation coefficients at different detection sites in the treatment group
Differences in gland deformation coefficients at different detection locations in the treatment group
Within the control group, significant differences in gland deformation coefficients were also observed at different examination sites (p &#x0003c; 0.05). The deformation coefficient of gland 6 was higher than the deformation coefficients for glands 1, 2, 3, 4, 5, 7, 8, 9, and 10, while the deformation coefficients for glands 3, 5, and 8 were higher than the deformation coefficient for gland 10 (<a href="#T5">Table 5</a>; <a href="#F4">Figure 4</a>)
Differences in gland deformation coefficients at different detection sites in the control group
Differences in gland deformation coefficients at different detection locations in the control group
In both groups, axial length increased with time after treatment. However, after 12&#x000a0;months of treatment, the degree of increase in axial length was significantly lower in the treatment group (0.15 &#x000b1; 0.13&#x000a0;mm) than in the control group (0.39 &#x000b1; 0.23&#x000a0;mm) (p &#x0003c; 0.05) (<a href="#T6">Table 6</a>)
Axial length before and after treatment in the two groups at 12&#x000a0;months
After 12&#x000a0;months of treatment, the spherical equivalent increased in 20 eyes (29.4%) in the treatment group, whereas it increased in 58 eyes (85.3%) in the control group, and the difference in the spherical equivalent between the two groups was statistically significant (p &#x0003c; 0.05) (<a href="#T7">Table 7</a>)
Spherical equivalent before and after treatment in the two groups at 12&#x000a0;months
These findings are in accordance with the significant change in the TBUT after 12&#x000a0;months of treatment in our patients
found that the average accuracy of the algorithm was 94.31%
and an average intersection ratio of 65.55%
Based on this tarsal gland segmentation algorithm
we developed a quantitative tarsal gland analysis model that can quantitatively analyze data from each tarsal gland in the upper eyelid
data were collected for only 10 tarsal glands in the central region of the upper eyelid
mainly because it is easier to collect complete data for the upper eyelid than for the lower eyelid
The glands in the central region play a major role in maintaining the stability of the microenvironment at the ocular surface
a certain amount of pressure is exerted not only on the cornea but also on the tarsal glands owing to the mechanics of the orthokeratology lens
which may lead to morphological changes in the glands closer to the central area
it is recommended that additional images of the tarsal gland be taken at the time of outpatient follow-up and that the main focus be on morphological changes of the tarsal gland in the central region
The refractive error of the human eye is closely related to both corneal curvature and axial length. An increase in negative refractive error is mainly related to an increase in axial length when the corneal curvature remains unchanged (<a href="#B1">Alhussain et al., 2022</a>)
both the treatment and control groups exhibited an increase in axial length after 12&#x000a0;months
After 12&#x000a0;months of treatment with an orthokeratology lens
the average increase in axial length in the treatment group was 0.15 &#x000b1; 0.13&#x000a0;mm
which was significantly less than that in the control group
The smaller change in axial length in the treatment group may be explained by a reduction in the average corneal curvature in the central region of the cornea through positive pressure exerted by the base curve of the lens
Light passing through the central region is then better concentrated at the fovea of the macula
The siphon principle of the reverse curve causes the corneal epithelial cells to migrate and accumulate at the reverse curve region
and the incident rays passing through this region are focused in front of the peripheral retina
This then forms a myopic defocus that inhibits the increase in axial length
Although the rate of increase in axial length was slower in the treatment group than in the control group of the present study
axial length was significantly longer in the treatment group than in the control group at each time point during the 12-month treatment period
the axial length increases with an increase in negative refractive error
provided that the difference in corneal curvature between the two eyes is insignificant
orthokeratology lenses are usually replaced each year
If each parameter (including corneal topography positioning
and changes in the eye axis) remains stable at this time
many parents will choose to have their child fitted for a new orthokeratology lens
the change in spherical equivalent after pupil dilation following use of the lens is often used to assess myopia control after 1&#x000a0;year of treatment
we also chose to compare changes in the spherical equivalent after lens use between the treatment and control groups
While eyes in the control group were not initially myopic
as the treatment group wore the orthokeratology lens for a long period of time
the changes in spherical equivalent became much higher in the control group than in the treatment group
This finding is in accordance with the significantly greater increase in axial length observed in the control group
Given the retrospective nature of the analysis
we were unable to evaluate infrared photographic data of the tarsal glands when the patients first wore the orthokeratology lens
and the abnormal morphological changes in the tarsal glands of the ipsilateral eyes before and after 1&#x000a0;year of wearing the lens were not further compared
These relationships should be examined in future studies
unilateral treatment with an orthokeratology lens was effective in controlling increases in axial length and negative refractive error in the myopic eye
thereby delaying the progression of myopia
Increases in axial length and negative refractive error were greater in the contralateral non-myopic eyes
The TBUT of myopic eyes tended to decrease with long-term use of the orthokeratology lens
Using an intelligent model to analyze the deformation coefficients
we found that long-term orthokeratology lens use significantly influenced morphological changes in the 10 tarsal glands in the central region
exerting a relatively greater effect on the glands closer to the central region
children undergoing single-eye treatment with an orthokeratology lens should be closely followed up for changes in spherical equivalent
and tear film function in both eyes to ensure that any abnormalities are detected and addressed using appropriate interventions in a timely manner
This will not only help to control the increase in the axial length of the non-myopic eye as early as possible but also ensure better comfort and reduce the likelihood of complications with long-term use
The raw data supporting the conclusion of this article will be made available by the authors
The studies involving human participants were reviewed and approved by the Ethics Committee (K2020-03-124) of the Fujian Provincial Hospital
Written informed consent to participate in this study was provided by the participants&#x02019; legal guardian/next of kin
All authors contributed to the article and approved the submitted version
The work was supported by Natural Science Foundation of Fujian Province
and Conghui Chen for their contributions to patient education
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations
Any product that may be evaluated in this article
or claim that may be made by its manufacturer
is not guaranteed or endorsed by the publisher
The role of peripheral ocular length and peripheral corneal radius of curvature in determining refractive error
<a href="https://pubmed.ncbi.nlm.nih.gov/33879375/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.1016/j.optom.2021.02.001">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=The+role+of+peripheral+ocular+length+and+peripheral+corneal+radius+of+curvature+in+determining+refractive+error&amp;btnG=">Google Scholar</a>
Tear film inflammatory cytokine upregulation in contact lens discomfort
<a href="https://pubmed.ncbi.nlm.nih.gov/30321605/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.1016/j.jtos.2018.10.004">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=Tear+film+inflammatory+cytokine+upregulation+in+contact+lens+discomfort&amp;btnG=">Google Scholar</a>
A review on the epidemiology of myopia in school children worldwide
<a href="https://pubmed.ncbi.nlm.nih.gov/31937276/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.1186/s12886-019-1220-0">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=A+review+on+the+epidemiology+of+myopia+in+school+children+worldwide&amp;btnG=">Google Scholar</a>
Potential of fluorescent nanoprobe in diagnosis and treatment of Alzheimer&#x00027;s disease
<a href="https://doi.org/10.2217/nnm-2022-0022">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=Potential+of+fluorescent+nanoprobe+in+diagnosis+and+treatment+of+Alzheimer's+disease&amp;btnG=">Google Scholar</a>
A novel quantitative index of meibomian gland dysfunction
<a href="https://pubmed.ncbi.nlm.nih.gov/32884858/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.1167/tvst.9.9.34">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=A+novel+quantitative+index+of+meibomian+gland+dysfunction,+the+meibomian+gland+tortuosity&amp;btnG=">Google Scholar</a>
Case report of Quarter&#x02013;Descemet membrane endothelial keratoplasty for Fuchs endothelial dystrophy
<a href="https://doi.org/10.1097/ICO.0000000000001008">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=Case+report+of+Quarter–Descemet+membrane+endothelial+keratoplasty+for+Fuchs+endothelial+dystrophy&amp;btnG=">Google Scholar</a>
The influence of overnight orthokeratology on ocular surface and meibomian glands in children and adolescents
<a href="https://pubmed.ncbi.nlm.nih.gov/26629959/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.1097/ICL.0000000000000196">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=The+influence+of+overnight+orthokeratology+on+ocular+surface+and+meibomian+glands+in+children+and+adolescents&amp;btnG=">Google Scholar</a>
Effects of orthokeratology lenses on the magnitude of accommodative lag and accommodativeconvergence/accommodation
<a href="https://pubmed.ncbi.nlm.nih.gov/26932215/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.11817/j.issn.1672-7347.2016.02.009">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=Effects+of+orthokeratology+lenses+on+the+magnitude+of+accommodative+lag+and+accommodativeconvergence/accommodation&amp;btnG=">Google Scholar</a>
&#x0201c;U-net: Convolutional networks for biomedical image segmentation,&#x0201d; in Medical image computing and computer-assisted intervention &#x02013; miccai 2015 (Cham: Springer)
<a href="https://doi.org/10.1007/978-3-319-24574-4_28">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=U-net:+Convolutional+networks+for+biomedical+image+segmentation&amp;btnG=">Google Scholar</a>
Influence of the interaction between parental myopia and poor eye habits when reading and writing and poor reading posture on prevalence of myopia in school students in Urumqi
<a href="https://pubmed.ncbi.nlm.nih.gov/34391397/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.1186/s12886-021-02058-3">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=Influence+of+the+interaction+between+parental+myopia+and+poor+eye+habits+when+reading+and+writing+and+poor+reading+posture+on+prevalence+of+myopia+in+school+students+in+Urumqi,+China&amp;btnG=">Google Scholar</a>
Interventions to slow progression of myopia in children
<a href="https://pubmed.ncbi.nlm.nih.gov/31930781/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.1002/14651858.CD004916.pub4">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=Interventions+to+slow+progression+of+myopia+in+children&amp;btnG=">Google Scholar</a>
<a href="https://pubmed.ncbi.nlm.nih.gov/26704137/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.1097/ICL.0000000000000190">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=Chinese+experiences+on+orthokeratology&amp;btnG=">Google Scholar</a>
The influence of overnight orthokeratology on ocular surface and dry eye-related cytokines IL-17A
<a href="https://pubmed.ncbi.nlm.nih.gov/32359968/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.1016/j.clae.2020.04.001">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=The+influence+of+overnight+orthokeratology+on+ocular+surface+and+dry+eye-related+cytokines+IL-17A,+IL-6,+and+PGE2+in+children&amp;btnG=">Google Scholar</a>
Orthokeratology lens wear for 2 years in children did not alter tear film lipid thickness by non-invasive interferometry
<a href="https://pubmed.ncbi.nlm.nih.gov/35223920/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.3389/fmed.2022.821106">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=Orthokeratology+lens+wear+for+2+years+in+children+did+not+alter+tear+film+lipid+thickness+by+non-invasive+interferometry&amp;btnG=">Google Scholar</a>
UNet&#x0002b;&#x0002b;: Redesigning skip connections to exploit multiscale features in image segmentation
<a href="https://pubmed.ncbi.nlm.nih.gov/31841402/">PubMed Abstract</a> &#x0007c; <a href="https://doi.org/10.1109/TMI.2019.2959609">CrossRef Full Text</a> &#x0007c; <a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=UNet++:+Redesigning+skip+connections+to+exploit+multiscale+features+in+image+segmentation&amp;btnG=">Google Scholar</a>
Effects of wearing orthokeratology lens on tear film and visual quality in adolescent patients with myopia
<a href="https://scholar.google.com/scholar?hl=en&amp;as_sdt=0%2C5&amp;q=Effects+of+wearing+orthokeratology+lens+on+tear+film+and+visual+quality+in+adolescent+patients+with+myopia&amp;btnG=">Google Scholar</a>
Lin J and Xue Y (2023) Effects of orthokeratology lenses on tear film and tarsal glands and control of unilateral myopia in children
Received: 30 March 2023; Accepted: 22 May 2023;Published: 21 June 2023
Copyright &#x000a9; 2023 Li, Lai, Zou, Guo, Lin, Lin and Xue. This is an open-access article distributed under the terms of the <a rel="license" href="http://creativecommons.org/licenses/by/4.0/" target="_blank">Creative Commons Attribution License (CC BY).</a> The use
distribution or reproduction in other forums is permitted
provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited
in accordance with accepted academic practice
distribution or reproduction is permitted which does not comply with these terms
&#x0002a;Correspondence: Jiawen Lin, <a id="encmail">bGp3QGZ6dS5lZHUuY24=</a>; Ying Xue, <a id="encmail">NTAyODczNzQwQHFxLmNvbQ==</a>
&#x02020;These authors share first authorship
Disclaimer:  All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations
Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher
94% of researchers rate our articles as excellent or goodLearn more about the work of our research integrity team to safeguard the quality of each article we publish
<a href="/articles/s41598-021-90796-1/metrics" data-track="click" data-track-action="view metrics" data-track-label="link" rel="nofollow">Metrics details</a>
Ischyromyids are a group of large rodents with the earliest fossil record known from the late Paleocene (Clarkforkian) of North America; they are considered the earliest fossil representatives of Rodentia of modern aspect
Ischyromyids dominated early Paleogene small-mammal assemblages of North America and in the latest Paleocene migrated to western Europe and to Asia; in the latter they survived only to the beginning of the late Eocene
Here we describe for the first time the calcanei of ischyromyids from the early middle Eocene of the Erlian Basin in Nei Mongol
These calcanei document the existence of three species
The morphology of the studied tarsal bones overall suggests ambulatory locomotion for these animals (‘slow cursors’)
similar to that of the coypu and porcupines
but one form shows more marked cursorial capabilities
These differences show that Chinese ischyromyids
had attained greater taxonomic diversity by the middle Eocene in Nei Mongol than estimated from dental remains
We also address the question of the morphological and ecological divergence of these ischyromyids in relation to their North American counterparts
as well as the issue of a direct dispersal route from North America to Asia in the early Eocene
If the family attribution of Namaparamys is correct
Africa would be the final continent colonized by this group
</a>Stratigraphic and geographic distribution of Ischyromyidae in China
(A) map of ischyromyid findings in China; yellow denotes Irdinmanhan findings in a province
green denotes older (?Bumbanian) findings; (B) panoramic view of Huheboerhe area; (C) detailed map of studied sites in the Erlian Basin; (D) stratigraphy of studied localities in the Erlian Basin
China; Irdinmanhan strata marked in yellow
(Maps and stratigraphic section created in Corel Draw X4 (v.14.0.0.567) by Łucja Fostowicz-Frelik; photograph taken by Łucja Fostowicz-Frelik)
Institute of Systematics and Evolution of Animals
Institute of Vertebrate Paleontology and Paleoanthropology
Zoological Museum of the Chinese Academy of Sciences
Order Rodentia Bowdich, 1821<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 31" title="Bowdich, T. E. An Analysis of Natural Classifications of Mammalia for the Use of Students and Travelers (J. Smith, 1821)." href="/articles/s41598-021-90796-1#ref-CR31" id="ref-link-section-d413007189e640">31</a>
Family Ischyromyidae Alston, 1876<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 32" title="Alston, E. R. On the classification of the order Glires. J. Zool. 44, 61–98 (1876)." href="/articles/s41598-021-90796-1#ref-CR32" id="ref-link-section-d413007189e646">32</a>
Genus Asiomys Qi, 1987<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 33" title="Qi, T. The middle Eocene Arshanto fauna (Mammalia) of Inner Mongolia. Ann. Carnegie Mus. 56, 1–73 (1987)." href="/articles/s41598-021-90796-1#ref-CR33" id="ref-link-section-d413007189e655">33</a>
Asiomys dawsoni Qi, 1987<a data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 33" title="Qi, T. The middle Eocene Arshanto fauna (Mammalia) of Inner Mongolia. Ann. Carnegie Mus. 56, 1–73 (1987)." href="/articles/s41598-021-90796-1#ref-CR33" id="ref-link-section-d413007189e663">33</a>
Figure <a data-track="click" data-track-label="link" data-track-action="figure anchor" href="/articles/s41598-021-90796-1#Fig3">3</a>A–E
</a>Ischyromyid calcanei from the early middle Eocene of the Erlian Basin
Explanatory line drawings (right side) show important morphological features
Note sustentacular facet marked pale yellow
(Photographs taken by Łucja Fostowicz-Frelik; drawings created in Corel Draw X4 (v.14.0.0.567) by Łucja Fostowicz-Frelik)
The calcaneal tuber is strongly compressed
but it resembles in shape those of species A and B
A long groove for the calcaneofibular ligament is impressed on its lateral side
The anterior plantar tubercle is large and swollen
and touches the brim of the calcaneocuboid surface
Systematic remark: The fossil was associated with Asiomys dentition found in the same spot
We attribute specimen IVPP V24417 to Asiomys dawsoni
based on this fact and its distinctive size (Asiomys being the largest rodent in the assemblage)
Asiomys is the only ischyromyid rodent known from the basal strata of the Irdin Manha Formation of Huheboerhe
Figure <a data-track="click" data-track-label="link" data-track-action="figure anchor" href="/articles/s41598-021-90796-1#Fig3">3</a>F–K
although in Paramys the calcaneal tuber is more compressed mediolaterally
inclined more strongly mediolaterally than in Notoparamys and Paramys
On the dorsal side of the calcaneal eminence
there is a flattened rough area (finely pitted)
marking the place of attachment of the lateral collateral ligaments binding the distal fibula and the astragalus with the calcaneus and stabilizing the astragalocalcaneal joint
The calcaneal tuber is not ‘pinched’ at its dorsal side but moderately compressed
thus there is no coracoid ridge posterior to the ectal facet
there is a long groove for the calcaneofibular ligament running askew
towards the dorsal surface of the calcaneal tuber
The groove for the calcaneofibular ligament is more weakly expressed than in the North American paramyines and arboreal sciurids
the medial process of the calcaneal tuber is much better developed and extending medially
The anterior plantar tubercle is also somewhat flattened and inclined medially and forms a well-marked calcaneal groove for the tendon of the flexor fibularis muscle
as in most of the rodent taxa (coypu and porcupines included)
and gently concave; it is also confluent and level with the cuboid pit
forming one round surface at the cranial end of the bone
Figure <a data-track="click" data-track-label="link" data-track-action="figure anchor" href="/articles/s41598-021-90796-1#Fig3">3</a>L–Q
The attachment for the calcaneal tendon forms a rounded concavity at the caudal side of the tuber
and is more horizontally and symmetrically located at the surface than in species A
The lateral surface of the calcaneal tuber bears a marked scar from the calcaneofibular ligament
not concave as in species A and in other compared taxa (e.g.
It is slightly longer anteroposteriorly and located more caudally (closer to the ectal facet) than in species A
one-half of the cranial part of the ectal facet
The medial edge of the sustentacular shelf bears a deep groove for the ‘spring ligament’
although its course is straighter along the proximodistal direction than in species A
with a slightly weaker medial component than in species A
is not typically ‘pinched’ into a sagittally oriented crest
more mediolaterally compressed than in the species A
Species B differs from the ground squirrels in the shape and location of the peroneal process
which is less extended laterally in species B than e.g.
although it is relatively much larger than in the coypu and porcupines
forms a shallow sink at the medial side of the surface
A Principal Component Analysis (PCA) was performed based on 14 measurements of the calcaneus. The analysis included the calcaneal measurements of five ischyromyid species (two described here as species A and B, and three comparative species from North America) and 16 extant large rodent species (Supplementary Table <a data-track="click" data-track-label="link" data-track-action="supplementary material anchor" href="/articles/s41598-021-90796-1#MOESM1">S1</a>)
The extant taxa represent six basic types of locomotor adaptations found in rodents: ambulatorial (terrestrial generalists)
</a>Principal component analysis of 14 metric parameters of rodent calcanei
The morphospace including paramyid calcanei from Nei Mongol in yellow circle
Lines connecting all data points represent a minimum spanning tree (MST) based on a Euclidean distance matrix
The loadings of the Components 1 and 2 shown at the corresponding axes
Strictly fossil taxa marked in red and pink
(Figure created in Corel Draw X4 (v.14.0.0.567) by Łucja Fostowicz-Frelik)
the PCA morphospace is divided into two (or even three) broad groups of ischyromyid locomotor adaptations: the ambulatorial species and those with more pronounced jumping or cursorial ability
Chinese taxa fall among typically large ambulatorial rodents
such as the coypu (Myocastor) and porcupines (Atherurus and Hystrix)
Closest to them there is the North American ischyromyid Quadratomus
which is somewhat shifted towards the cursorial species and can be thus distinguished as differently specialized (more cursorial)
which may imply some jumping and slightly scansorial locomotor adaptations for Ischyromys and those of typical agile generalist species for Reithroparamys
the results of the PCA analysis point to general differences in the structure of the calcaneus
between Asian and North American ischyromyid species
Asian species seem to differ less from each other than the North American ones do
reflecting the overall greater species diversity and coverage of a wider niche spectrum of the North American ischyromyids
and a large peroneal process observed in most ischyromyid species (including these studied herein) indicate rather poor cursoriality
their ankle joint structure allows for a large freedom of foot movements in different planes
A medially extended sustentaculum tali together with a long and helically twisted ectal facet indicate a large degree of sliding between the calcaneus and astragalus along their articular facets
which makes possible a great degree of foot torsion resulting in foot eversion and inversion
This effect is further enhanced by an extended calcaneocuboid facet that is gently concave and oriented perpendicularly to the long axis of the calcaneus in species A
As complete or even partial postcranial skeletons are unknown for the Asian ischyromyids
we can surmise their general locomotor adaptations based on calcaneal morphology which
although not in striking contrast with their North American counterparts
these herbivores probably were not direct competitors of ischyromyids
(Drawing made in Corel Draw X4 (v.14.0.0.567) by Łucja Fostowicz-Frelik)
by the IVPP field parties during 2004–2012 seasons
GPS data (geographic coordinates and the height above sea level) were recovered for each finding
All data generated or analysed during this study are included in this published article (and its Supplementary Information files)
Application of phylogenetic taxonomy to poorly resolved crown clades: a stem-modified node-based definition of Rodentia
The morphology of Tribosphenomys (Rodentiaformes
Mammalia): phylogenetic implications for basal Glires
New late Paleocene rodents (Mammalia) from Big Multi Quarry
High-level phylogeny of early tertiary rodents: dental evidence
Cranial anatomy and relationships of a new ctenodactyloid (Mammalia
Rodentia) from the early Eocene of Hubei Province
Ischyromyidae in Evolution of Tertiary Mammals in North America
Middle Eocene rodents from Peruvian Amazonia reveal the pattern and timing of caviomorph origins and biogeography
Oldest ctenodactyloid tarsals from the Eocene of China and evolution of locomotor adaptations in early rodents
Glires in The Rise of Placental Mammals; Origins
and Relationships of the Major Extant Clades (eds
D.) 145–158 (Johns Hopkins University Press
New ctenodactyloid rodents from the Erlian Basin
China and the phylogenic relationships of Eocene Asian ctenodactyloids
(ed.) Late Cretaceous and Cenozoic Mammals of North America
Biostratigraphy and Geochronology (Columbia University Press
Systematics of the late Paleocene and early Eocene Rodentia (Mammalia) from the Clarks Fork Basin
Les paramyidae (Rodentia) de l’Eocène inférieur du bassin de Paris
Les rongeurs de l’Eocène inférieur et moyen d’Europe occidentale
biochronologie et paléobiogéographie des niveaux-repères MP 7 à MP 14
First Clarkforkian equivalent land mammal age in the latest Paleocene basal Sparnacian facies of Europe: fauna
Early Eocene rodents (Mammalia) from Shandong Province
Fossil mammals from the early Eocene Wutu formation of Shandong Province
New early Eocene rodents from the Zaysan Basin in The Flora and Fauna of the Zaysan Basin (ed
Discovery of Ischyromyinae (Rodentia: Mammalia) from the Middle Eocene of North China
An ailuravine rodent from the lower Eocene Cambay formation at Vastan
Reithroparamyine rodent from the Eocene of Namibia
The Paleogene of Asia: mammals and stratigraphy
Mammalia) from the Erlian Basin: evidence for the Early Tertiary Bumbanian Land Mammal Age in Nei-Mongol
New stratigraphic data from the Erlian Basin: implications for the division
and definition of Paleogene lithological units in Nei Mongol (Inner Mongolia)
mammalian evolution and its response to environmental changes in Erlian Basin
Comments on Paleogene localities and stratigraphy in the Erlian Basin
Eocene fossil rodent assemblages from the Erlian Basin (Inner Mongolia
Middle Eocene Ischyromyidae (Mammalia: Rodentia) from the Shanghuang fissures
An Analysis of Natural Classifications of Mammalia for the Use of Students and Travelers (J
The middle Eocene Arshanto fauna (Mammalia) of Inner Mongolia
and function of the tarsus in late Cretaceous Eutheria and Paleocene Primates in Primate Locomotion (ed
The hind limb skeleton and cursorial adaptations of the Plio-Pleistocene rabbit Hypolagus beremendensis
Ecomorphological analysis of the astragalo-calcaneal complex in rodents and inferences of locomotor behaviours in extinct rodent species
The tarsal-metatarsal complex of caviomorph rodents: anatomy and functional-adaptive analysis
Tarsal morphology and locomotor adaptation of some late middle Eocene caviomorph rodents from Peruvian Amazonia reveal early ecological diversity
Skeletal indicators of locomotor adaptations in living and extinct rodents
The early Tertiary rodents of the family Paramyidae
Rodent and lagomorph morphotype adaptations
and relationships: some postcranial attributes analyzed in Evolutionary Relationships among Rodents
(eds) Handbook of the Mammals of the World: Lagomorphs and Rodents I (Lynx Edicions
Oldest known euarchontan tarsals and affinities of Paleocene Purgatorius to Primates
A new genus of stem lagomorphs (Mammalia: Glires) from the middle Eocene of the Erlian Basin Nei Mongol
Strenulagus (Mammalia: Lagomorpha) from the middle Eocene Irdin Manha formation of the Erlian Basin
A large mimotonid from the middle Eocene of China sheds light on the evolution of lagomorphs and their kin
Small mammal fauna from Wulanhuxiu (Nei Mongol
China) implies the Irdinmanhan-Sharamurunian (Eocene) faunal turnover
Palaeocene and Eocene Mixodontia (Glires) of Mongolia and China
Middle Eocene small mammals from Liguanqiao Basin of Henan Province and Yuanqu Basin of Shanxi Province
Paleogene mammalian fauna exchanges and the paleogeographic pattern in Asia
New trends in adaptive radiation of Early Tertiary rodents (Rodentia
A new Eocene anagalid (Mammalia: Euarchontoglires) from Mongolia and its implications for the group’s phylogeny and dispersal
A gliriform tooth from the Eocene of the Erlian Basin (Nei Mongol
China) and the premolar morphology of anagalidan mammals at a crossroads
Oligocene rodents (Mammalia) from East Mesa
a new ctenodactyloid rodent subfamily from the Miocene of Baluchistan
A new tarkadectine primate from the Eocene of Inner Mongolia
China: phylogenetic and biogeographic implications
Biostratigraphy and diversity of Paleogene perissodactyls from the Erlian Basin of Inner Mongolia
middle Eocene of Jiangsu: history of discovery and significance
The mid-Tertiary Ctenodactylidae (Rodentia
PAST: paleontological statistics software package for education and data analysis
The ICS International Chronostratigraphic Chart
Classification of Mammals above the Species Level (Columbia University Press
<a data-track="click" data-track-action="download citation references" data-track-label="link" rel="nofollow" href="https://citation-needed.springer.com/v2/references/10.1038/s41598-021-90796-1?format=refman&amp;flavour=references">Download references</a>
2015/18/E/NZ8/00637 from the National Science Centre (Cracow
the Strategic Priority Research Program of Chinese Academy of Sciences (XDB26000000) and the National Natural Science Foundation of China Grant No
and an AMNH Kalbfleisch Postdoctoral Research Fellowship to SL-T
The fieldwork was also supported by the Special Fund for Fossil Excavation and Preparation
Key Laboratory of Vertebrate Evolution and Human Origins
CAS Center for Excellence in Life and Paleoenvironment
Łucja Fostowicz-Frelik &amp; Sergi López-Torres
New York Consortium in Evolutionary Primatology
ŁF-F designed the study and wrote the initial draft of the paper
and approved the final version of the manuscript
The authors declare no competing interests
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations
<a data-test="citation-link" data-track="click" data-track-action="download article citation" data-track-label="link" data-track-external="" rel="nofollow" href="https://citation-needed.springer.com/v2/references/10.1038/s41598-021-90796-1?format=refman&amp;flavour=citation">Download citation</a>
DOI: https://doi.org/10.1038/s41598-021-90796-1
Anyone you share the following link with will be able to read this content:
a shareable link is not currently available for this article
Sign up for the Nature Briefing: Anthropocene newsletter — what matters in anthropocene research