Effect of Overnight Wear Orthokeratology Lenses on Corneal Shape and Tears

Effects of orthokeratology on corneal reshaping and the delaying of axial eye growth in children

Purpose

To investigate the inhibition of myopia progression and axial elongation in children wearing orthokeratology (OK) lenses, as well as to evaluate the status of corneal reshaping, this study explores the relationship between changes in central corneal curvature (K-value) and e-value induced by OK lenses and axial elongation.

Methods

In this study, it is planned to select children aged 8-15 who wear orthokeratology lenses at the Pediatric Ophthalmology and Strabismus Clinic of the Second Affiliated Hospital of Dalian Medical University. All children will undergo slit lamp examination, visual acuity assessment, computerized refraction, intraocular pressure measurement, biometry, and corneal topography examination before lens wear and at 1 month, 3 months, and 6 months after lens wear in the pediatric ophthalmology clinic. Based on age (lower age group (8 < age ≤12 years); higher age group (12 < age ≤15 years)) and baseline equivalent spherical (SE) value (mild myopia group (-1.00 D < SE ≤ -3.25D); moderate myopia group (-3.25 D < SE ≤ -6.00 D)), four groups will be formed by pairing these factors. Suitable data will be selected according to inclusion and exclusion criteria, and different groups will be included. Data will be organized, and statistical analysis will be performed using SPSS software to obtain the results. The expected results will be discussed and analyzed.

Results

After wearing OK lenses, all four groups achieved good visual acuity at follow-up. At 6 months, there were no significant differences in visual acuity among the four groups (P = 0.149, >0.05). There were no significant differences in refractive error among the four groups (P = 0.066, >0.05). Baseline axial length differed significantly among the four groups (P = 0.000, <0.001), with the LM group having longer axial length than the LL group (P < 0.001, paired samples t-test), and the HM group having longer axial length than the HL group (P < 0.001, paired samples t-test). However, there were no significant differences in axial length change compared to baseline among the groups at 1 month, 3 months, and 6 months (P 1 = 0.053; P 3 = 0.557; P 6 = 0.329, >0.05). Significant differences were observed in corneal flat K-value change compared to baseline among the four groups at 1 month, 3 months, and 6 months (P 1 = 0.001, P 3 = 0.001, P 6 = 0.004, <0.05). There were no significant differences in e-value change among the groups at 1 and 3 months (P 1 = 0.205, P 3 = 0.252, >0.05), but significant differences were found in e-value change compared to baseline at 6 months (P 6 = 0.010, <0.05). Multiple regression analysis with changes in central corneal flat K-value and e-value as independent variables and axial elongation as the dependent variable showed a correlation between e-value change at 6 months and axial elongation (P = 0.004, <0.05), indicating a negative correlation.

Conclusion

Orthokeratology (OK) lenses effectively improve myopic children's vision by reshaping the cornea, leading to reduced central corneal curvature and flattening of its anterior surface. The effectiveness of OK lenses is not significantly affected by age or initial myopia severity. Children of varying ages and myopia levels experience similar levels of axial length control with OK lens wear. Changes in corneal shape due to OK lenses affect axial elongation, with greater changes in corneal morphology associated with smaller increases in axial length.

Comparison of trial lens and computer-aided fitting in orthokeratology: A multi-center, randomized, examiner-masked, controlled study

PURPOSE

To compare the efficacy and safety between traditional lens fitting and computer-aided fitting methods for orthokeratology (OrthoK) in the Chinese population.

METHODS

A multi-center, examiner-masked, randomized controlled study was conducted with a one-year follow-up period, enrolling 280 participants with spherical equivalent (SE) ranging from -0.5D to -4.0D. Participants were assigned to either the computer-aided orthokeratology fitting group (trial group) or the traditional lens fitting group (control group) using stratified randomization based on age (8 to 13 years, 13 to 18 years, and ≥ 18 years) to ensure a minimum of 30 cases in each sub-age group. Ocular examinations included visual acuity, objective and subjective refraction, corneal endothelial cell density, corneal topography, intraocular pressure, axial length, and ocular health assessment. Successful lens-correction was defined as the residual refraction with the OK lens, which should not exceed ± 0.5D, and/or an uncorrected visual acuity of no worse than 0.1 logMAR. Statistical analysis involves t-tests, analysis of variance, and Chi-squared tests.

RESULTS

215 subjects were included in the statistical analysis (109 in the trial group and 106 in the control group). In both groups, compared to baseline data, the uncorrected visual acuity (UCVA) improved significantly, with SE reduced and central corneal curvature flattened greatly after wearing OrthoK lens (P < 0.05 for all). Compared to the control group, the trial group exhibited a higher successful rate in correcting UCVA (93.6 % vs. 84.0 %, P = 0.03) and slightly better correction in refraction (77.1 % vs. 66.0 %, P = 0.07) at 1-month follow-up. However, no significant differences were observed in the axial length elongation, corneal changes, or the incidence of adverse events between the two groups.

CONCLUSION

These findings indicate the higher efficiency and slightly better performance in correcting myopia and improving UCVA of computer-aided lens fitting approach compared to the traditional one, but similar outcomes in controlling axial elongation.

Characteristics of the Ocular Surface in Myopic Child Candidates of Orthokeratology Lens Wear

INTRODUCTION

The purpose of this study was to investigate the characteristics of objective ocular surface parameters using non-invasive objective instruments in children with myopia who are candidates for orthokeratology lens wear.

METHODS

Children with myopia who are candidates for orthokeratology lens wear were retrospectively investigated. The subjects were divided into three age groups. The Keratograph 5M and LipiView interferometry were used to assess non-invasive tear meniscus height (TMH), non-invasive tear film break-up time (NIBUT), conjunctival hyperemia redness score (RS), meibomian gland loss (MGL) score, lipid layer thickness (LLT), and blink pattern analysis, including the number of partial blinks (PB) and total blinks (TB), as well as the partial blink rate (PBR).

RESULTS

A total of 1119 children with myopia (2070 eyes) aged 7-18 years were selected. The mean TMH, NIBUT, and LLT of the subjects was 0.21 mm, 12.45 s, and 65.28 nm, respectively. The mean RS and upper and lower MGL scores were 0.64, 1.00, and 1.06, respectively. The mean PB, TB, and PBR was 5.13, 6.46, and 0.81, respectively. Age was significantly correlated to all ocular surface parameters (p = 0.00), except for PB. NIBUT and LLT did not differ between male participants and female participants (all p > 0.05). TMH, RS, and upper and lower MGL were significantly higher in male participants than in female participants (all p < 0.01). In addition, NIBUT was positively associated with TMH (r = 0.13, p = 0.00) and LLT (r = 0.28, p = 0.00). Both upper and lower MGL were positively correlated with TMH, PB, and TB (all p = 0.00), whereas upper MGL was negatively correlated with NIBUT and LLT (all p < 0.05). TB was negatively correlated with NIBUT and LLT (all p = 0.00). PB had no relation with TMH, NIBUT, and LLT (all p > 0.05). In addition, PBR was positively correlated with NIBUT and LLT (all p = 0.00) but not with TMH, RS, or MGL (all p > 0.05). Overall, 57.00% had a TMH ≤ 0.2 mm, 43.20% had a NIBUT ≤ 10 s, 48.10% had an LLT ≤ 60 nm, and 88.10% had a PBR > 0.4.

CONCLUSIONS

Child orthokeratology candidates have enhanced tear secretion and increased meibomian gland deficiency with aging. In addition, the adult dry eye diagnostic criteria may apply to orthokeratology candidates aged 12-18 years but should be lower for younger candidates. Given the proportion of abnormal risk, it is necessary to assess tear film status and blink pattern by reliable and feasible objective examination before fitting orthokeratology.

Impact of Overnight Wear of Orthokeratology Lens on Thickness of Tear Film Lipid Layer in Children with Myopia

BACKGROUND

To elucidate the influence of overnight wear of orthokeratology (OOK) lenses on the thickness of the tear lipid layer (LLT).

METHODS

We conducted a retrospective cross-sectional study of children who visited The First Affiliated Hospital of USTC between July and September 2021. LLT and blinking dynamics were assessed. Diopters and corneal topography were also recorded.

RESULTS

The number of children enrolled in this program was 402 (804 eyes). One hundred and seventy-one children (342 eyes, 79 males and 92 females) aged 4 - 17 years (10.59 ± 2.54 years) who never wore OOK were included in the control group, while 231 children (462 eyes, 121 males and 110 females) aged 7 - 18 years (11.09 ± 2.24 years) who wore OOK for more than 1 week were included in the observation group. Compared to the control group with an LLT of 58.5 ± 18.19 nm, the OOK group exhibited a significant decrease in the LLT value to 54.42 ± 17.60 nm. In addition, the LLT in females was significantly thicker than that in males in both the control (male 54.78 ± 16.56 nm, female 61.70 ± 18.95 nm) and observation groups (male 51.88 ± 16.68 nm, female 57.21 ± 18.18 nm). It is worth noting that the influence of wearing OOK on the LLT value was only detected up to 18 months. Eighteen months later, there was almost no difference in LLT between the control and observation groups. We also noted that there was no change in LLT correlated to the surface regularity index/surface asymmetry index.

CONCLUSION

Wearing OOK can affect tear film LLT within the first 18 months after wear. More attention should be given to children wearing OOK for less than 18 months, especially males.

Development of corneal contact lens materials and current clinical application of contact lenses: A review

Unlike conventional glasses, corneal contact lenses (CLs) can directly contact the surface of the tear film through the application of biopolymer materials, to achieve therapeutic and cosmetic purposes. Since the advent of polymethylmethacrylate, a material that has gained widespread use and attention, statistically, there are now more than 150 × 106 people around the world who wear corneal contact lenses. However, the associated complications caused by the interaction of contact lenses with the ocular surface, tear film, endogenous and environmental microorganisms, and components of the solution affect nearly one-third of the wearer population. The application of corneal contact lenses in correcting vision and myopia control has been widely recognized. With the development of related materials, corneal contact lenses are applied to the treatment of ocular surface diseases, including corneal bandage lenses, drug-loaded corneal contact lenses, biosensors, and other new products, while minimizing the side effects associated with CL wear. This paper summarized the development history and material properties of CLs, focused on the current main clinical applications and mechanisms, as well as clarified the possible complications in wearing therapeutic contact lenses and the direction for improvement in the future.

The Effects of Spectacles or Orthokeratology on the Tear Film in Children and Adolescents

INTRODUCTION

Myopia prevalence among adolescents is increasing annually. While orthokeratology (OK) is effective for controlling myopia progression, it may also be detrimental. We investigated tear film parameters [including tear mucin 5AC (MUC5AC) concentration] in children and adolescents with myopia treated with spectacles or OK compared with those with emmetropia.

METHODS

This prospective case-control study enrolled children (aged 8-12 years; 29 and 39 with myopia treated with OK and spectacles, respectively, and 25 with emmetropia) and adolescents (aged 13-18 years; 38 and 30 with myopia treated with OK and spectacles, respectively, and 18 with emmetropia). We recorded the ocular surface disease index (OSDI), visual analog scale (VAS) score, tear meniscus height (TMH), noninvasive tear breakup time (NIBUT), meibomian gland score (meiboscore), ocular redness score, and tear MUC5AC concentration in the emmetropia, spectacle (after 12 months of spectacle wearing), and OK (baseline, and after 1-, 3-, 6-, and 12-month use) groups. We observed changes from baseline to 12 months in the OK group and compared parameters among the spectacle, 12-month OK, and emmetropia groups.

RESULTS

The 12-month OK group differed significantly from the spectacle and emmetropia groups in most indicators among children and adolescents (P < 0.05). Differences were not noticeable between the spectacle and emmetropia groups (only PVAS < 0.05 among the children). In the OK group, the 12-month NIBUT was significantly decreased (P < 0.05) in both age groups; the upper meiboscore was increased at 6 and 12 months (both P < 0.05) among children; ocular redness scores were higher at 12 months than at baseline (P = 0.007), 1 month (P < 0.001), and 3 months (P = 0.007) among children; and the MUC5AC concentration was decreased at 6 and 12 months among adolescents, but only at 12 months among children (all P < 0.05).

CONCLUSIONS

Long-term OK can negatively influence the tear film in children and adolescents. Moreover, changes are masked by spectacle wearing.

TRIAL REGISTRATION

This trial is registered with "ChiCTR2100049384."

Effect of overnight orthokeratology lenses on tear film stability in children

PURPOSE

To assess the tear film surface quality after orthokeratology using an automated Medmont E300 corneal topographer.

METHODS

Children who wore orthokeratology lenses for more than one year were selected in this retrospective study. Tear film disruption (TFD) and central tear film disruption (cTFD) were measured with Medmont E300 corneal topographer at initial and each follow-up visit after fitting with orthokeratology lenses, providing a nominal value from 0 (perfect) to 1 (poor). Tear film surface quality before and after ortho-k treatment was compared.

RESULTS

145 children using orthokeratology lenses were observed. TFD and cTFD significantly increased at 1-day follow up (TFD, t = -17.3, P < 0.001; cTFD, t = -10.4, P < 0.001). This change remained consistent through to 12-months visit (TFD, F = 51.1, P < 0.001; cTFD, F = 28.0, P < 0.001). A sub-group of n = 11 children were discontinued for 1-month before being refit with OrthoK lenses of a different design. Similarly, there was a significant increase in TFD compared to pre-orthoK scans (0.172 ± 0.161), but this returned to baseline levels after ceasing lens wear (0.084 ± 0.059). A sub-group of monocular OrthoK wearers (n = 23) found that TFD and cTFD values increased in eyes with monocular lens-wearing but remained stable in the lateral eyes.

CONCLUSIONS

Objective measurements of tear-film quality are reduced in children after fitting with orthokeratology lenses, but return to baseline after 1-month of lens cessation. It is of importance to ensure tear film surface quality is continuously monitored throughout use of orthoK lenses.

Long-term changes in the ocular surface during orthokeratology lens wear and their correlations with ocular discomfort symptoms

PURPOSE

To evaluate the changes in ocular surface parameters during orthokeratology lens wear and determine their correlations with ocular discomfort symptoms.

METHODS

Fifty individuals were enrolled in this prospective pilot study. Clinical evaluation of the ocular surface included the ocular surface disease index, slit-lamp examination, Keratograph 5M, optical quality analysis system, and corneal staining. After baseline examinations, clinical tests were performed at 1 day, 1 week, 1 month, 3 months, 6 months, and 12 months after orthokeratology lens wear. Correlations between ocular discomfort symptoms and signs of ocular discomfort were evaluated.

RESULTS

Overall ocular surface disease index score and two subscale scores (ocular symptoms and vision-related function) significantly increased at the 3-month visit (P < 0.05), and decreased to levels close to baseline at the12-month visit (P > 0.05). The basic objective scatter index and the mean tear film objective scatter index increased, peaking at 3-month visit (P < 0.05) and gradually decreased thereafter. The modulation transfer function cut-off significantly decreased at the 3-month visit (P < 0.05). During the 12-month study period, the overall ocular surface disease index score and vision-related function score were significantly and positively correlated with the basic objective scatter index and mean tear film objective scatter index (P < 0.05). After 1 week of lens wear, Grade 1 corneal staining increased to 16.4 %, mostly involving the central and inferior cornea.

CONCLUSIONS

Orthokeratology lens wear increased ocular discomfort symptoms and decreased the function of tear film, mainly within 3 months of lens wear. Tear-related visual function parameters were correlated with ocular discomfort. A new parameter, tear film objective scatter index, measured with the optical quality analysis system, was more sensitive in detecting the quality and stability of tear film than traditional indicators.

Changes in Shape Discrimination Sensitivity Under Glare Conditions After Orthokeratology in Myopic Children: A Prospective Study

Purpose

To investigate changes in shape discrimination under mesopic conditions with and without glare after orthokeratology in myopic children.

Methods

This prospective study included 79 eyes of 79 myopic children (ages: 8-16 years). Shape discrimination thresholds (SDTs) were measured using radial frequency patterns, with a radial frequency of 4 cycles/360°, a peak spatial frequency of 3 cycles per degree, a contrast of 20%, and a mean radius of 1.5 degrees. SDT under mesopic conditions with and without glare was measured before orthokeratology and again at 1 week and 1 month after orthokeratology. Changes in the SDTs and their relationships to baseline ocular parameters were analyzed.

Results

SDTs with glare decreased significantly at 1 week (-0.08 ± 0.15 log(arcsec), P < 0.001) and 1 month (-0.09 ± 0.15 log(arcsec), P < 0.001) after orthokeratology. SDTs without glare remained stable (P = 0.81 and P = 1.00, respectively). The difference between SDTs with and without glare also decreased significantly at 1 week (-0.10 ± 0.17 log(arcsec), P < 0.001) and at 1 month (-0.08 ± 0.18 log(arcsec), P = 0.001) after orthokeratology. Based on a multivariate analysis, the greater decrease in SDT with glare after 1 month of orthokeratology was associated with a higher baseline spherical equivalent refraction.

Conclusions

Orthokeratology resulted in improved shape discrimination in myopic children under mesopic conditions but only when measured in the presence of glare.

Application of orthokeratology on myopia control and its effect on ocular surface and meibomian gland function in Chinese myopic adolescents

Purpose

This study aimed to investigate the influence of orthokeratology (OK) on myopia control and ocular surface and meibomian gland function in myopic adolescents.

Methods

A prospective study was conducted over a 12-month period. The subjects were classified into two groups, namely, the OK lens group and the frame glasses control group. Axial length, corneal curvature, ocular surface, and meibomian gland parameters were measured at baseline, 1, 3, 6, and 12 months after wearing OK lenses.

Results

The axial length growth rate in the OK group was significantly slower than in the control group (P < 0.01). The naked eye vision and the ocular surface disease index (OSDI) scores recorded 1, 3, 6, and 12 months after wearing OK lenses were significantly higher than the scores recorded before wearing OK lenses. There was no significant difference in other ocular parameters at each follow-up time point compared with pre-wearing (P > 0.05). After using the OK lens for 6 months, the OSDI score and corneal fluorescein staining (CFS) score increased significantly (P < 0.001), but there were no significant differences in other parameters among the groups. No infectious keratitis occurred during the study.

Conclusion

These results provide evidence that the use of OK lenses can control the axial growth and progress rate of myopia compared with frame glasses. During the 12-month follow-up, although wearing OK lenses may have aggravated dry eye symptoms, each patient's ocular surface and meibomian gland function did not change significantly, indicating that the use of OK lenses is a relatively safe modality for the control of myopia in adolescents.

Integrating Clinical Data and Tear Proteomics to Assess Efficacy, Ocular Surface Status, and Biomarker Response After Orthokeratology Lens Wear

Purpose

This study evaluated the efficacy and ocular surface status of Breath-O Correct, novel orthokeratology (OK) lenses, worn overnight for 3 months. Lens-induced changes in the tear proteome were evaluated.

Methods

Thirty-one subjects, aged 19 to 26 years with refractive error from -1.00 to -5.00 D, were randomly assigned 1:1 to the treatment or control group. Refraction, visual acuity, corneal integrity, biomechanics and endothelial health, ocular surface changes, and subjective symptoms were assessed at the baseline, one-month, and three-month visits. The tear proteome was characterized over time using sequential window acquisition of all theoretical ion spectra mass spectrometry.

Results

Lenses improved uncorrected visual acuity and reduced spherical powers with similar efficacy to other OK lenses. Significant reductions (P < 0.05) in corneal hysteresis (11.12 ± 1.12 to 10.38 ± 1.36 mm Hg) and corneal resistance factor (11.06 ± 1.32 to 9.90 ± 1.45 mm Hg) were observed in the treatment group after one month of lens wear, whereas other assessed factors remained unchanged. Thirteen and eight differentially expressed proteins were found after one month and three months of lens wear, respectively. Two proteins (proline-rich protein 27 and immunoglobulin V regions) were differentially expressed at both visits.

Conclusions

Over a three-month period, Breath-O Correct lenses were overall safe, well tolerated, efficacious in refractive power reduction, and comparable with other OK lenses. Furthermore, their use caused only minor noninflammatory protein expression changes in the tear proteome.

Translational Relevance

This study investigated the safety of orthokeratology contact lenses on the ocular surface in molecular aspects and standard clinical parameters.

The Association between Fourier Parameters and Clinical Parameters in Myopic Children Undergoing Orthokeratology

Purpose: To explore how Fourier parameters are associated with axial length growth (ALG) and clinical parameters in children who underwent orthokeratology.Materials and Methods: A total of 267 children received orthokeratology. Baseline cycloplegic autorefraction was performed. Axial length was measured at baseline and one year after the lens dispatch, and the difference was defined as ALG. Corneal topography was performed at the same two visits. Central treatment zone (CTZ) was identified from the difference between the two tangential maps, and its center distance to corneal center was defined as decentration. A relative refractive corneal power (RCRP) map was derived by subtracting the center value from every point on the one-year axial map. It was decomposed into 3 Fourier components: a mean (F0), a single-cycle sinewave (F1), and a double-cycle sinewave (F2). Linear regressions were used to reveal the association between ALG and these parameters.Results: At baseline, the age was 10.18 ± 1.48 year, spherical equivalent (SE) was - 3.10 ± 1.15D, astigmatism was 1.17 ± 0.58D, and axial length was 24.69 ± 0.81 mm. The mean ALG was 0.181 ± 0.22 mm. In multiple regression, ALG was negatively associated with F1 (p < .001), not F0 and F2. Amplitude-wise, F0 and F1 were correlated with decentration (p < .01) and SE (p < .01), and F2 was associated with astigmatism (p < .001). Direction-wise, F1 was correlated with decentration (p < .001) and F2 was associated with astigmatism (p < .001).Conclusions: Among Fourier parameters, F0 and F1 were negatively associated with ALG in myopic children undergoing orthokeratology. Their associations to SE and CTZ decentration may partially explain the effect on ALG retardation.

Blur Detection Sensitivity Increases in Children Using Orthokeratology

Purpose

To investigate changes in blur detection sensitivity in children using orthokeratology (Ortho-K) and explore the relationships between blur detection thresholds (BDTs) and aberrations and accommodative function.

Methods

Thirty-two children aged 8–14 years old who underwent Ortho-K treatment participated in and completed this study. Their BDTs, aberrations, and accommodative responses (ARs) were measured before and after a month of Ortho-K treatment. A two forced-choice double-staircase procedure with varying extents of blur in three images (Tumbling Es, Lena, and Street View) was used to measure the BDTs. The participants were required to judge whether the images looked blurry. The BDT of each of the images (BDT_Es, BDT_Lena, and BDT_Street) was the average value of the last three reversals. The accommodative lag was quantified by the difference between the AR and the accommodative demand (AD). Changes in the BDTs, aberrations, and accommodative lags and their relationships were analyzed.

Results

After a month of wearing Ortho-K lenses, the children’s BDT_Es and BDT_Lena values decreased, the aberrations increased significantly (for all, P ≤0.050), and the accommodative lag decreased to a certain extent [T(31) = 2.029, P = 0.051]. Before Ortho-K treatment, higher-order aberrations (HOAs) were related to BDT_Lena (r = 0.463, P = 0.008) and the accommodative lag was related to BDT_Es (r = −0.356, P = −0.046). After one month, no significant correlations were found between the BDTs and aberrations or accommodative lags, as well as between the variations of them (for all, P ≥ 0.069).

Conclusion

Ortho-K treatment increased the children’s level of blur detection sensitivity, which may have contributed to their good visual acuity.

Low concentration atropine combined with orthokeratology in the treatment of axial elongation in children with myopia: A meta-analysis

OBJECTIVE

To evaluate the effect of low concentration atropine combined with Orthokeratology (OK) lens compared with the OK lens on the changes of axial length in children with moderate and low myopia by meta-analysis.

METHODS

Databases such as PubMed, Web of Science, Embase, and Cochrane Library were comprehensively searched to collect related studies on atropine combined with the OK lens in the treatment of children with moderate and low myopia. The retrieval time was from the establishment of the database to December 2020. The standardized mean difference (SMD) and its 95% confidence interval (CI) were selected as the effect to analyze the changes of the axial length of the eye axis in children with low and moderate myopia treated with low concentration atropine combined with OK lens.

RESULTS

A total of eight articles were included in this study. Compared with OK lens treatment, low concentration atropine combined with the OK lens significantly slowed down the axial elongation of low and moderate myopia, SMD = -0.68(95% CI: -0.86--0.50, p < 0.05). According to the subgroup analysis of treatment time, when the treatment time was less than or equal to 6 months, SMD = -0.63(95% CI: -0.88--0.37, p < 0.05), when the treatment time was 1 year, SMD = -0.76(95% CI: -1.08--0.43, p < 0.05), and when the treatment time was 2 years, SMD = -0.69(95% CI: -1.07--0.31, p < 0.05).

CONCLUSION

Low concentration atropine combined with the OK lens is more effective than the OK lens in the treatment of children with low to moderate myopia in reducing axial elongation.

Does Orthokeratology Wearing Affect the Tear Quality of Children?

Orthokeratology is currently known as one of the most effective methods of myopia control in the process of rapid deterioration of the global myopia prevalence. As orthokeratology is widely used, it is necessary to evaluate its complications reasonably and accurately. Eye surface problems in children, such as dry eyes, have received increasing attention. At present, there is no conclusive evidence on how orthokeratology affects the ocular surface, especially the tears. To our knowledge, this is the first study to explore the relationship between orthokeratology lenses and tears through meta-analysis. However, it is still challenging to get a convincing conclusion and a higher level of evidence in this meta-analysis. Reasons for this include limitation of study design, lack of clarity on important confounding factors, lack of appropriate statistical tools, and other biases. This paper will analyze the dilemma existing in the current research from different perspectives to provide meaningful information for future studies in this field.

Tear Lipid Layer Thickness in Children after Short-Term Overnight Orthokeratology Contact Lens Wear

Meibomian gland lipid secretion is important to the stability of the tear film and ocular surface comfort. Changes in the tear film’s lipid layer thickness (LLT) after orthokeratology treatment may reflect underlying changes to the meibomian gland function. The purpose of this study was to investigate the features of the tear lipid layer in normal children and the effects of short-term orthokeratology treatment. Altogether, 163 myopic children (age: 10.7 ± 1.9 years, 8–15 years; 71 males) with no contact lens use history were enrolled in this study, of whom 56 were successfully fitted with orthokeratology lenses and completed the 1-month study. The tear film’s LLT (average, maximum, and minimum) and blinking pattern were measured by a LipiView® interferometer in 163 participants at baseline and in 56 orthokeratology participants at 1 week and 1 month after overnight lens wear. Results show that LLT (average) was 58.09 ± 21.66 nm in Chinese normal children. LLT was significantly correlated with rate of partial blinks at every follow-up (all $p<0.05$ ). Compared to baseline, the LLT (average and minimum) and partial blinks (number and rate) at 1 week and 1 month after orthokeratology treatment both significantly increased, and the increase of LLT was correlated with elevation of rate of partial blinks. In conclusion, LLT was shown to be elevated after short-term overnight orthokeratology treatment and was related to change in rate of partial blinks. Further studies are needed to clarify the long-term effect and the underlying mechanism.

Analysis of tear film spatial instability for pediatric myopia under treatment

In Taiwan, the prevalence of myopia in children between 6 and 18 years old is over 80%, and high myopia accounts for over 20%, which turned out to be in the leading place worldwide. Orthokeratology and low-dose atropine are proven treatments to reduce myopia progression, though the potential corneal disturbances remain an issue in young populations. The alteration of the tear film is widely discussed but there is no consensus to date, so we aim to investigate the tear film spatial instability in children with myopia control using atropine or orthokeratology. Thirty-eight treatment-naïve participants and 126 myopic children under treatments were enrolled. The ocular surface homeostasis, spatial distribution of tear break-up, and high-order aberrations (HOAs) of the corneal surface were assessed. We found out that myopic children treated with either atropine or orthokeratology showed ocular surface homeostasis similar to that in treatment-naïve children. Nevertheless, children treated with orthokeratology presented higher HOAs (p < 0.00001) and a tendency of the first tear break-up zone at the inner half of the cornea (p = 0.04). This unique spatial instability of the tear film associated with myopia treatment might provide a more focused way of monitoring the pediatric tear film instability.

Tracking the Reflective Light Particles Spreading on the Cornea: An Emerging Assessment for Tear Film Homeostasis

Purpose

To implement an emerging noninvasive approach for assessing the dynamic tear film (TF) homeostasis.

Methods

The video records of dynamic TF from 12 healthy orthokeratology lens wearers were obtained by a clinically available TF analyzer and decomposed as image sequences. The trajectories of TF particles were analyzed by two tracking models, the full-span model (FSM) and the fixed-duration model (FDM). FSM tracked a particle for a complete opening blink cycle, while FDM tracked 1 second of the same cycle. A power-law fitting operation \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}{\rm{MMS}}\left( t \right) = {\rm{\alpha }} \times {t^{ - {\rm{\beta }}}}\end{document} was used to extract homeostasis markers based on the tracking model for each subject.

Results

Comparing two tracking models (N = 6), only one subject had statistical difference in averaged momentary moving speed (MMS; P = 0.0488), while none had significant difference in averaged momentary moving direction (MMD). However, both models showed good correlations in average MMS (ρ = 0.94, P = 0.0048) and MMD (ρ = 1.00, P < 0.0001) and all extracted homeostasis markers [α, β, MMS(0.1), and MMS(2.0)]. Assessing interblink reliability in these markers under FDM tracking (N = 12), only one subject in the MMS (0.1) and another subject in the MMS (2.0) were outside 95% limits of agreement, respectively.

Conclusions

FDM is a good alternative to FSM and has tracking properties of higher efficiency and easier implementation. The homeostasis markers under FDM tracking showed a good interblink consistence; therefore this approach will be a promising method for analyzing dynamic TF homeostasis in future practice.

Translational Relevance

FDM analytical architecture can practice the past experimental platform on a TF analyzer to obtain homeostasis markers of TF.

The Influence of Overnight Orthokeratology on Ocular Surface and Meibomian Gland Dysfunction in Teenagers with Myopia

Purpose

The aim of this study was to investigate the effect of overnight orthokeratology (OOK) on ocular surface and meibomian gland dysfunction in teenagers with myopia.

Methods

A total of 59 subjects were recruited in this prospective study. The following tests were performed before and after 1, 3, 6, 12, and 24 months of OOK lens wear, including ocular surface disease index (OSDI) questionnaire, slit-lamp examination, and Keratograph 5M.

Results

No infectious keratitis occurred during the study. OSDI scores increased gradually and reached the maximum at 6 months of OOK wear (P < 0.001). The meniscus height was significantly increased at 1 and 3 months after the initiation of OOK (P=0.006, P=0.035). The corneal fluorescein staining at 1, 3, 6, 12, and 24 months after wearing OOK were all increased than the prewearing level with significant difference (P=0.014, P=0.036, P < 0.001, P < 0.001, and P=0.008, respectively). The first and the average tear film NIKBUT were all higher than the prewearing level, but there was no significant difference between every follow-up time points (P > 0.05). The lid margin abnormalities were significantly increased (P=0.003, P=0.038, and P=0.015) at 6, 12, and 24 months after the initiation of OOK. There was no significant difference in the meibomian gland orifice scores at each follow-up time points compared to the prewearing level (P > 0.05). The meibomian gland lipid secretion scores after wearing OOK were higher than those of the prewearing level, however, without statistically significant difference (P > 0.05). No significant differences of the degree of difficulty of lipid excretions were detected after the initiation of OOK (P > 0.05). There was no significant difference in meibomian gland dropout scores between all follow-up time points and the prewearing level (P=1.000).

Conclusion

OOK increased the symptoms of dry eye and decreased the function of tear film by affecting the meniscus height and BUT. OOK did not affect the function of meibomian glands.Clinical Study registration number: ChiCTR18000185708.

A New Method to Analyze the Relative Corneal Refractive Power and Its Association to Myopic Progression Control With Orthokeratology

Purpose

We present a new method for analyzing relative corneal refractive power (RCRP) in children undergoing orthokeratology and explore its potential association to effective myopic control

Methods

A total of 55 children aged 8 to 12 years participated in the study. Axial growth was calculated as the difference in axial length before and 1 year after orthokeratology. Growth <0.30 mm was considered as effective control. Corneal topography was obtained before and 4 months after lens dispatch. The topography was divided into 36 10° slices and the maximal RCRP (mRCRP) in each was calculated and fitted into a model that integrated the effects of mean refractive power (M), corneal asymmetry (f1), and astigmatism (f2). The relationship between the probability of achieving effective control and the modulation of mRCRP was analyzed with logistic regression.

Results

A total of 45 subjects achieved effective control, but for 10 the treatment was ineffective. The M-values were not different between the groups. Modulations of mRCRP were significantly larger in the effective than the ineffective group (1.17 vs. 0.64 diopters [D] for f1, P = 0.02; 0.85 vs. 0.35 D for f2, P = 0.03). The probability to achieve effective control increased with modulation of mRCRP (P = 0.02). With a peak mRCRP > 4.5 D, a subject had an above 80% chance to achieve effective control.

Conclusions

The new method reveals that how the combination of spherical equivalent (SE), corneal asymmetry, and astigmatism determines modulation of the mRCRP and a large amplitude of modulation is associated with a higher probability of effective myopic control.

Translational Relevance

Our finding enables clinicians to estimate the outcome early and provides new insights to lens design.

Long-Term Changes in Straylight Induced by Overnight Orthokeratology: An Objective Measure Using the Double-Pass System

Purpose: To map the time course of changes in intraocular straylight of the human eye 1 year after initial lens wearing for orthokeratology treatment using the objective double-pass technique. Materials and Methods: A total of 35 subjects (19 males and 16 females) completed the study. The mean age was 11.46 ± 2.33 years (range, 8-16 years). All subjects were fitted with spherical four-zone orthokeratology lenses following the procedures recommended by the lens manufacturer. The subjects were required to wear the lens for at least eight consecutive hours at night. After lens removal during the daytime, objective scattering index (OSI) was evaluated using the double-pass technique (OQAS-II, Visiometrics, Terrassa, Spain) prior to lens dispatch (baseline), followed by evaluations at 1 week, 1 month, 6 months, and 12 months after the initial lens wearing. Longitudinal changes were fitted to a model containing both an impairing and recovery component, and the results were based on an extrapolation between the visits. Results: OSI rose quickly following lens wearing, reaching its highest level (double that of baseline values) by approximately 1.47 months. However, the recovery phase was slow and modest. One year after the initial lens wearing, OSI exhibited a 20% recovery from the peak level, but remained 63% higher than the baseline level. Conclusions: Intraocular straylight immediately increased flowing lens wearing, and this change reaches maximal level around 1 month after lens wearing. Slow but significant recoveries of optical quality subsequently followed.