Clinical performance of an orthokeratology lens fitted with the aid of a computer software in Chinese children

A protocol for a single center, randomized, controlled trial assessing the effects of spectacles or orthokeratology on dry eye parameters in children and adolescents

Background

The prevalence of myopia among adolescents is increasing precipitously in China, and the popularity of orthokeratology (OK) lenses as an effective treatment for controlling myopia progression is rising. This protocol assessed and compared the clinical dry eye parameters in children and adolescents with myopia treated with spectacles or OK lenses.

Methods and analysis

This single-masked randomized control trial will include 300 participants (aged 8-17 years) with myopia treated with OK lens (study group) or spectacles (control group). We will record the ocular surface disease index, visual analog scale score, noninvasive tear breakup time, tear meniscus height, meibomian gland score, ocular redness score, visual acuity, tear Matrix Metalloproteinase-9 concentration, tear Lymphotoxin alpha levels at baseline, and after 1-, 3-, 6-, and 12-month.

Discussion

This study will be a standardized, scientific, clinical trial designed to evaluate the dry eye parameters in children and adolescents with myopia treated with OK lenses for myopia control.

Ethics and dissemination

This study has been approved by the Ethics Committee of He Eye Specialist Hospital [ethics approval number: IRB(2023)K024.01]. Before participating in the trial, written informed consent will be obtained from all patient's parents or guardians. The findings of this study will be showcased at both local and international conferences and will also be submitted for publication in reputable peer-reviewed journals.

Trial registration number

Clinicaltrials.gov: NCT06023108 {2a, 2b}.

Artificial Intelligence-Assisted Prescription Determination for Orthokeratology Lens Fitting: From Algorithm to Clinical Practice

OBJECTIVES

To explore the potential of artificial intelligence (AI) to assist prescription determination for orthokeratology (OK) lenses.

METHODS

Artificial intelligence algorithm development followed by a real-world trial. A total of 11,502 OK lenses fitting records collected from seven clinical environments covering major brands. Records were randomly divided in a three-way data split. Cross-validation was used to identify the most accurate algorithm, followed by an evaluation using an independent test data set. An online AI-assisted system was implemented and assessed in a real-world trial involving four junior and three senior clinicians.

RESULTS

The primary outcome measure was the algorithm's accuracy (ACC). The ACC of the best performance of algorithms to predict the targeted reduction amplitude, lens diameter, and alignment curve of the prescription was 0.80, 0.82, and 0.83, respectively. With the assistance of the AI system, the number of trials required to determine the final prescription significantly decreased for six of the seven participating clinicians (all P <0.01). This reduction was more significant among junior clinicians compared with consultants (0.76±0.60 vs. 0.32±0.60, P <0.001). Junior clinicians achieved clinical outcomes comparable to their seniors, as 93.96% (140/149) and 94.44% (119/126), respectively, of the eyes fitted achieved unaided visual acuity no worse than 0.8 ( P =0.864).

CONCLUSIONS

AI can improve prescription efficiency and reduce discrepancies in clinical outcomes among clinicians with differing levels of experience. Embedment of AI in practice should ultimately help lessen the medical burden and improve service quality for myopia boom emerging worldwide.

Benefits and risks of orthokeratology treatment: a systematic review and meta-analysis

BACKGROUND

This meta-analysis reviews the evidence for the risks and benefits associated with orthokeratology (OK) treatment compared with other methods of myopia control in children and adults.

METHODS

A systematic search of Cochrane Central Register of Controlled Trials, Pubmed, Embase and Ovid was conducted from database inception to 22nd August 2021. Studies that reported on risks, visual and ocular biometric effects of OK in patients > 5 years of age with myopia (- 0.75 to - 6.00D) were included. Main outcomes are change in axial length and any adverse event.

RESULTS

Fourty-five papers were included in this systematic review and meta-analysis. The quality of data was variable and of moderate certainty, and selection bias likely skewed the results towards a relative benefit for OK. The rate of axial elongation in children was lower for OK treatment compared to other treatment modalities at one year (MD - 0.16 mm, 95% CI - 0.25 to - 0.07). Rate of change in axial length in children rebounded after OK discontinuation compared to participants who continued treatment (MD 0.10 mm, 95% CI 0.06 to 0.14). Adults and children wearing OK were up to 3.79 times more likely to experience an adverse event when compared with conventional contact lenses (OR 3.79, 95% CI 1.24 to ll.), though this evidence base is underdeveloped and requires additional well-designed studies for substantial conclusions to be drawn.

CONCLUSIONS

OK arrests myopia progression while in use, however, there remain unanswered questions about the optimal duration of treatment, discontinuation effects and long-term risk for adverse events.

Long-Term Efficacy of Orthokeratology to Control Myopia Progression

OBJECTIVES

To assess the efficacy of orthokeratology in controlling the rate of myopia progression in children and investigate the factors associated with axial length (AL) growth rate with an average of 48 months of orthokeratology lens wear.

METHODS

As a retrospective study, 84 subjects underwent relatively complete ophthalmologic examinations. After initial lens wear, AL was measured on average every 12 months. The linear mixed-effects model (LMM) was used to compare the differences in AL growth rates at each time interval. The contribution of the independent variables to AL change was assessed using multiple linear regression.

RESULTS

In the LMM, there was a significant difference in the AL growth rate ( P <0.001) at each follow-up. The growth rate of AL was associated with initial AL, spherical equivalent refractive errors (SERs) and diameter of lens ( P =0.045, 0.003 and 0.037, respectively). When the baseline age was included as a factor, the influence of initial AL and SER became insignificant in the analysis, whereas age and diameter of lens were significantly correlated with the growth rate of AL ( P< 0.001 and P< 0.001, respectively). There were significant differences in growth rates among different age groups.

CONCLUSIONS

Results of the study demonstrated that the factors associated with lower growth rate in AL were older age and longer diameter of lens.

Orthokeratology in adults and effect on quality of life

OBJECTIVE

To determine changes in various ocular parameters of adults wearing orthokeratology (ortho-k) lenses and their levels of satisfaction and quality of life (QoL) after commencing treatment.

METHODS

Adults aged 18-38 years, with mild to moderate myopia and astigmatism < 1.50D, were wearing ortho-k lenses for one year. Data collection, which included history taking, refraction, axial length (AL), corneal topography, corneal biomechanics, and biomicroscopy examination, was performed at baseline and every 6 months during the study period. The level of satisfaction with the treatment and QoL was determined via questionnaires.

RESULTS

Forty-four subjects completed the study. AL was shortened significantly at the 12-month visit: AL -0.03 (-0.45 to 0.13) mm compared to baseline (p < 0.05). A significant number of subjects in both groups presented with overall and central corneal staining, but the majority were mild (Grade 1). Central endothelial cell density was reduced by 40/mm² (loss rate 1.4 %) (p < 0.05). High scores were obtained in the satisfaction questionnaire, with no significant differences between visits. At the 12-month visit, NEI-RQL-42 total score, dependence on correction, activity limitation, appearance, and satisfaction with the treatment all significantly increased compared to baseline values.

CONCLUSIONS

Results suggest that ortho-k can be an effective and safe myopia correction technique for adults with low to moderate myopia, improving daytime vision without serious adverse events. Satisfaction with ortho-k lens wear was high, particularly those who were dependent on vision correction and found spectacles or contact lenses limiting specific activities or cosmetically undesirable.

Interventions for myopia control in children: a living systematic review and network meta-analysis

BACKGROUND

Myopia is a common refractive error, where elongation of the eyeball causes distant objects to appear blurred. The increasing prevalence of myopia is a growing global public health problem, in terms of rates of uncorrected refractive error and significantly, an increased risk of visual impairment due to myopia-related ocular morbidity. Since myopia is usually detected in children before 10 years of age and can progress rapidly, interventions to slow its progression need to be delivered in childhood.

OBJECTIVES

To assess the comparative efficacy of optical, pharmacological and environmental interventions for slowing myopia progression in children using network meta-analysis (NMA). To generate a relative ranking of myopia control interventions according to their efficacy. To produce a brief economic commentary, summarising the economic evaluations assessing myopia control interventions in children. To maintain the currency of the evidence using a living systematic review approach.  SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register), MEDLINE; Embase; and three trials registers. The search date was 26 February 2022.  SELECTION CRITERIA: We included randomised controlled trials (RCTs) of optical, pharmacological and environmental interventions for slowing myopia progression in children aged 18 years or younger. Critical outcomes were progression of myopia (defined as the difference in the change in spherical equivalent refraction (SER, dioptres (D)) and axial length (mm) in the intervention and control groups at one year or longer) and difference in the change in SER and axial length following cessation of treatment ('rebound').  DATA COLLECTION AND ANALYSIS: We followed standard Cochrane methods. We assessed bias using RoB 2 for parallel RCTs. We rated the certainty of evidence using the GRADE approach for the outcomes: change in SER and axial length at one and two years. Most comparisons were with inactive controls.

MAIN RESULTS

We included 64 studies that randomised 11,617 children, aged 4 to 18 years. Studies were mostly conducted in China or other Asian countries (39 studies, 60.9%) and North America (13 studies, 20.3%). Fifty-seven studies (89%) compared myopia control interventions (multifocal spectacles, peripheral plus spectacles (PPSL), undercorrected single vision spectacles (SVLs), multifocal soft contact lenses (MFSCL), orthokeratology, rigid gas-permeable contact lenses (RGP); or pharmacological interventions (including high- (HDA), moderate- (MDA) and low-dose (LDA) atropine, pirenzipine or 7-methylxanthine) against an inactive control. Study duration was 12 to 36 months. The overall certainty of the evidence ranged from very low to moderate. Since the networks in the NMA were poorly connected, most estimates versus control were as, or more, imprecise than the corresponding direct estimates. Consequently, we mostly report estimates based on direct (pairwise) comparisons below. At one year, in 38 studies (6525 participants analysed), the median change in SER for controls was -0.65 D. The following interventions may reduce SER progression compared to controls: HDA (mean difference (MD) 0.90 D, 95% confidence interval (CI) 0.62 to 1.18), MDA (MD 0.65 D, 95% CI 0.27 to 1.03), LDA (MD 0.38 D, 95% CI 0.10 to 0.66), pirenzipine (MD 0.32 D, 95% CI 0.15 to 0.49), MFSCL (MD 0.26 D, 95% CI 0.17 to 0.35), PPSLs (MD 0.51 D, 95% CI 0.19 to 0.82), and multifocal spectacles (MD 0.14 D, 95% CI 0.08 to 0.21). By contrast, there was little or no evidence that RGP (MD 0.02 D, 95% CI -0.05 to 0.10), 7-methylxanthine (MD 0.07 D, 95% CI -0.09 to 0.24) or undercorrected SVLs (MD -0.15 D, 95% CI -0.29 to 0.00) reduce progression.  At two years, in 26 studies (4949 participants), the median change in SER for controls was -1.02 D. The following interventions may reduce SER progression compared to controls: HDA (MD 1.26 D, 95% CI 1.17 to 1.36), MDA (MD 0.45 D, 95% CI 0.08 to 0.83), LDA (MD 0.24 D, 95% CI 0.17 to 0.31), pirenzipine (MD 0.41 D, 95% CI 0.13 to 0.69), MFSCL (MD 0.30 D, 95% CI 0.19 to 0.41), and multifocal spectacles  (MD 0.19 D, 95% CI 0.08 to 0.30). PPSLs (MD 0.34 D, 95% CI -0.08 to 0.76) may also reduce progression, but the results were inconsistent. For RGP, one study found a benefit and another found no difference with control. We found no difference in SER change for undercorrected SVLs (MD 0.02 D, 95% CI -0.05 to 0.09). At one year, in 36 studies (6263 participants), the median change in axial length for controls was 0.31 mm. The following interventions may reduce axial elongation compared to controls: HDA (MD -0.33 mm, 95% CI -0.35 to 0.30), MDA (MD -0.28 mm, 95% CI -0.38 to -0.17), LDA (MD -0.13 mm, 95% CI -0.21 to -0.05), orthokeratology (MD -0.19 mm, 95% CI -0.23 to -0.15), MFSCL (MD -0.11 mm, 95% CI -0.13 to -0.09), pirenzipine (MD -0.10 mm, 95% CI -0.18 to -0.02), PPSLs (MD -0.13 mm, 95% CI -0.24 to -0.03), and multifocal spectacles (MD -0.06 mm, 95% CI -0.09 to -0.04). We found little or no evidence that RGP (MD 0.02 mm, 95% CI -0.05 to 0.10), 7-methylxanthine (MD 0.03 mm, 95% CI -0.10 to 0.03) or undercorrected SVLs (MD 0.05 mm, 95% CI -0.01 to 0.11) reduce axial length. At two years, in 21 studies (4169 participants), the median change in axial length for controls was 0.56 mm. The following interventions may reduce axial elongation compared to controls: HDA (MD -0.47mm, 95% CI -0.61 to -0.34), MDA (MD -0.33 mm, 95% CI -0.46 to -0.20), orthokeratology (MD -0.28 mm, (95% CI -0.38 to -0.19), LDA (MD -0.16 mm, 95% CI -0.20 to  -0.12), MFSCL (MD -0.15 mm, 95% CI -0.19 to -0.12), and multifocal spectacles (MD -0.07 mm, 95% CI -0.12 to -0.03). PPSL may reduce progression (MD -0.20 mm, 95% CI -0.45 to 0.05) but results were inconsistent. We found little or no evidence that undercorrected SVLs (MD -0.01 mm, 95% CI -0.06 to 0.03) or RGP (MD 0.03 mm, 95% CI -0.05 to 0.12) reduce axial length. There was inconclusive evidence on whether treatment cessation increases myopia progression. Adverse events and treatment adherence were not consistently reported, and only one study reported quality of life. No studies reported environmental interventions reporting progression in children with myopia, and no economic evaluations assessed interventions for myopia control in children.

AUTHORS' CONCLUSIONS

Studies mostly compared pharmacological and optical treatments to slow the progression of myopia with an inactive comparator. Effects at one year provided evidence that these interventions may slow refractive change and reduce axial elongation, although results were often heterogeneous. A smaller body of evidence is available at two or three years, and uncertainty remains about the sustained effect of these interventions. Longer-term and better-quality studies comparing myopia control interventions used alone or in combination are needed, and improved methods for monitoring and reporting adverse effects.

Compression Factor and Visual Performance in Adults Treated With Orthokeratology

OBJECTIVES

To investigate the effect of compression factor on visual performance in orthokeratology (ortho-k).

METHODS

Myopic adults were fitted with ortho-k lenses with either a 0.75 diopter (D) or 1.75 D compression factor. Higher-order aberrations (HOAs), corneal topography, and responses to the National Eye Institute/Refractive Error Quality of Life Instrument-42 questionnaire were measured at baseline and 6-month and 12-month follow-up along with a satisfaction questionnaire. Subjective refraction, high-contrast, and low-contrast visual acuity were measured at baseline and 1-day, 1-week, 6-month, and 12-month follow-up.

RESULTS

Forty-four myopic (mean spherical equivalent refraction: -3.66±0.84 D) adults (median age 25 years) completed the 12-month follow-up. After ortho-k lens wear, levels of satisfaction of vision after waking were significantly higher than vision before sleep for both compression factors (both P<0.01). The increased compression factor (ICF) resulted in less myopia at the 1-week visit (P=0.04) and better high-contrast unaided visual acuity at the 1-day visit (P=0.03) compared with the conventional compression factor (CCF). No other significant differences were observed for the compression factor for treatment zone diameter, lens decentration, or any subjective measurements. Individual HOA terms , , , and were significantly higher in the CCF group (0.75 D) (all P<0.05). The HOA visual Strehl ratio decreased significantly after lens wear (P<0.001) but did not vary with the compression factor.

CONCLUSIONS

An ICF did not result in clinically significant differences in subjective refraction, visual acuity, unaided vision, or the total ocular HOA profile compared with a CCF (0.75 D) in myopic adults after long-term ortho-k lens wear.

One-year results of the Variation of Orthokeratology Lens Treatment Zone (VOLTZ) Study: a prospective randomised clinical trial

Purpose

To present the 1‐year results of the Variation of Orthokeratology Lens Treatment Zone (VOLTZ) Study, which aims to investigate the myopia control effect of orthokeratology (ortho‐k) lenses with different back optic zone diameters (BOZD).

Method

Children, aged 6 to <11 years, having myopia −4.00 D to −0.75 D, were randomly assigned to wear ortho‐k lenses with 6 mm (6‐MM group) or 5 mm (5‐MM group) BOZD. Data collection included changes in refraction, vision, lens performance and binding, ocular health conditions, axial length and characteristics of the treatment zone (TZ) area.

Results

The 1‐year results of 34 and 36 subjects (right eye only) in the 6‐MM and 5‐MM groups, respectively, are presented. No significant differences in baseline demographics were found between the groups (p > 0.05). The first‐fit success rates, based on satisfactory centration at the 1‐month visit, were 100% and 94% respectively. Horizontal TZ size was 0.92 mm and 0.72 mm smaller in the 5‐MM group at the 6‐month and 12‐month visits, respectively (p < 0.05). At the 12‐month visit, no significant between‐group differences were found in the incidence of corneal staining (low grade only), lens binding and visual performance (all p > 0.05). Axial elongation was slower in the 5‐MM group (0.04 ± 0.15 mm) than the 6‐MM group (0.17 ± 0.13 mm) (p = 0.001). A significant positive correlation was observed between the horizontal TZ size and axial elongation (r = 0.36, p = 0.006).

Conclusion

Clinical performance of the two ortho‐k lenses was similar, indicating that a smaller BOZD (5 mm) did not affect lens performance or ocular integrity. However, a smaller BOZD led to a reduced TZ, with retardation of axial elongation by 0.13 mm compared to conventional 6 mm BOZD ortho‐k lenses after one year of lens wear.

Practice of orthokeratology in Algeria: a retrospective study

PURPOSE

To report the practice of orthokeratology (OK) in Algeria and to investigate the visual outcomes, safety and subjective responses with this technique in myopes.

METHODS

A retrospective chart review of 48 participants using OK lenses since January 2010 were included in the study. Lenses were selected and fitted according to the manufacturer's recommendations using their respective software and the number of lenses required for a successful fit was recorded. Visual acuity (VA) in logMAR units and biomicroscopic findings were recorded for each visit. Subjective ratings was determined with analogue rating scale was filled in by the investigator, the participants were divided into Group 1 (> 4.00D) and Group 2 (< 3.75D) myopic groups for analysis.

RESULTS

First lens fitting success rate of 64.58%. There was also a significant difference between the BCVA at baseline and VA at Day 1 (P < 0.05), and no significant difference at Day 7, Day 30 and the final visit (P = 0.51, P = 0.93, P = 0.62, respectively), for Group 2. There was a significant difference between the BCVA at baseline and VA at Day 1, 7, 30 and the final visit (P < 0.05), for Group 1. the patients of the second group were happier but the results from the survey were not statistically significant (P = 0.10), no serious complication was reported.

CONCLUSION

the technique was efficient and safe as we didn't have any serious complication, with a high success rate for first lens fitting.

Orthokeratology with increased compression factor (OKIC): study design and preliminary results

OBJECTIVE

To present the study design and the baseline data of a prospective cohort study investigating the safety, refractive correction and effectiveness of myopia control in subjects fitted with orthokeratology (ortho-k) lenses of different compression factors.

METHODS AND ANALYSIS

This study is a 2-year longitudinal, double-masked, partially randomised study. Myopic children aged between 6 and 10 years are recruited and they may choose to participate in either the ortho-k or spectacle-wearing group. Subjects in the ortho-k group are randomly assigned to wear ortho-k lenses of either conventional compression factor (CCF, 0.75 D) or increased compression factor (ICF, 1.75 D). For the ortho-k subjects, the time and between-group effects within the first month of lens wear were analysed.

RESULTS

Sixty-nine ortho-k subjects (CCF: 34; ICF: 35) and 30 control subjects were recruited. There were no significant differences in baseline demographic data among the three groups of subjects (p>0.19). At the 1-month visit, the first fit success rates were 97% and 100% in the CCF and ICF ortho-k group, respectively. A higher percentage of ICF subjects could achieve full correction (CCF: 88.2%; ICF: 94.3%). The change in axial length was significantly higher in the ICF group (CCF, 0.003 mm; ICF, -0.031 mm) (p<0.05). No significant between-group differences in daytime vision or in the coverage and depth of corneal staining between the two ortho-k groups (p>0.05) were observed at any visit.

CONCLUSION

ICF did not compromise the corneal integrity and the lens centration within the first month of lens wear. The preliminary performance of ortho-k lenses with ICF of 1.00D shows that it was safe to be used in the longer term for the investigation of myopia control.

TRIAL REGISTRATION NUMBER

NCT02643342.

Orthokeratology in adults and factors affecting success: Study design and preliminary results

OBJECTIVE

To report the study design and one month's preliminary results of a randomized, single-masked, one-year prospective study of orthokeratology (ortho-k) in adults wearing lenses of different compression factors.

METHODS

Adults aged 18-38 years, with myopia of -0.75 to -5.00 D and astigmatism < 1.50 D, were recruited and randomly assigned into two groups: a conventional compression factor or Jessen Factor (CCF) group (compression factor = 0.75 D) and an increased (extra 1.00D) compression factor (ICF) group. Clinical outcomes, including spherical equivalent refraction (SER) reduction, visual acuity, corneal hysteresis (CH) and corneal resistance factor (CRF), and signs and symptoms were collected at the one-month follow-up visit. Indicators of the level of satisfaction and quality of life after commencing treatment were determined via a satisfaction questionnaire and the NEI-RQL-42 questionnaire.

RESULTS

Baseline data from 26 CCF and 24 ICF participants were analysed and no significant differences were observed between the two groups (p > 0.05). The first fit success rates were 90 % for CCF group and 83 % for the ICF group, SER reductions were 97 % and 95 % for the CCF and ICF group, respectively, with uncorrected high-contrast visual acuity of -0.06 (-0.18 to 0.42) and 0.00 (-0.16 to 0.52), respectively (p > 0.05) at the 1-month visit. Overall, the incidence of corneal staining was 77 % in the CCF and 79 % in ICF group; central corneal staining was 15 % and 33 %, respectively. However, the differences of corneal staining between the groups did not reach significance in any visit (p > 0.05). The main complaint from participants was glare (both groups). No significant differences in CRF and CH were found in the first month (p > 0.05). Both groups recorded high scores in the level of satisfaction questionnaire, with no significant differences between groups (p > 0.05). Compared with baseline scores, 1-month NEI-RQL-42 subscales of dependence on correction, appearance, and satisfaction with correction significantly increased, and the glare score significantly decreased in both groups (all p < 0.05).

CONCLUSIONS

The majority of participants were satisfied with the treatment and no serious corneal adverse effects were observed. These results demonstrate that ortho-k lenses of default and increased compression factor (1D) demonstrated similar clinical performance and ortho-k can be a safe and well-accepted option for myopia correction in adults, but long-term observation is warranted.

Interventions to slow progression of myopia in children

BACKGROUND

Nearsightedness (myopia) causes blurry vision when one is looking at distant objects. Interventions to slow the progression of myopia in children include multifocal spectacles, contact lenses, and pharmaceutical agents.

OBJECTIVES

To assess the effects of interventions, including spectacles, contact lenses, and pharmaceutical agents in slowing myopia progression in children.

SEARCH METHODS

We searched CENTRAL; Ovid MEDLINE; Embase.com; PubMed; the LILACS Database; and two trial registrations up to February 2018. A top up search was done in February 2019.

SELECTION CRITERIA

We included randomized controlled trials (RCTs). We excluded studies when most participants were older than 18 years at baseline. We also excluded studies when participants had less than -0.25 diopters (D) spherical equivalent myopia.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods.

MAIN RESULTS

We included 41 studies (6772 participants). Twenty-one studies contributed data to at least one meta-analysis. Interventions included spectacles, contact lenses, pharmaceutical agents, and combination treatments. Most studies were conducted in Asia or in the United States. Except one, all studies included children 18 years or younger. Many studies were at high risk of performance and attrition bias. Spectacle lenses: undercorrection of myopia increased myopia progression slightly in two studies; children whose vision was undercorrected progressed on average -0.15 D (95% confidence interval [CI] -0.29 to 0.00; n = 142; low-certainty evidence) more than those wearing fully corrected single vision lenses (SVLs). In one study, axial length increased 0.05 mm (95% CI -0.01 to 0.11) more in the undercorrected group than in the fully corrected group (n = 94; low-certainty evidence). Multifocal lenses (bifocal spectacles or progressive addition lenses) yielded small effect in slowing myopia progression; children wearing multifocal lenses progressed on average 0.14 D (95% CI 0.08 to 0.21; n = 1463; moderate-certainty evidence) less than children wearing SVLs. In four studies, axial elongation was less for multifocal lens wearers than for SVL wearers (-0.06 mm, 95% CI -0.09 to -0.04; n = 896; moderate-certainty evidence). Three studies evaluating different peripheral plus spectacle lenses versus SVLs reported inconsistent results for refractive error and axial length outcomes (n = 597; low-certainty evidence). Contact lenses: there may be little or no difference between vision of children wearing bifocal soft contact lenses (SCLs) and children wearing single vision SCLs (mean difference (MD) 0.20D, 95% CI -0.06 to 0.47; n = 300; low-certainty evidence). Axial elongation was less for bifocal SCL wearers than for single vision SCL wearers (MD -0.11 mm, 95% CI -0.14 to -0.08; n = 300; low-certainty evidence). Two studies investigating rigid gas permeable contact lenses (RGPCLs) showed inconsistent results in myopia progression; these two studies also found no evidence of difference in axial elongation (MD 0.02mm, 95% CI -0.05 to 0.10; n = 415; very low-certainty evidence). Orthokeratology contact lenses were more effective than SVLs in slowing axial elongation (MD -0.28 mm, 95% CI -0.38 to -0.19; n = 106; moderate-certainty evidence). Two studies comparing spherical aberration SCLs with single vision SCLs reported no difference in myopia progression nor in axial length (n = 209; low-certainty evidence). Pharmaceutical agents: at one year, children receiving atropine eye drops (3 studies; n = 629), pirenzepine gel (2 studies; n = 326), or cyclopentolate eye drops (1 study; n = 64) showed significantly less myopic progression compared with children receiving placebo: MD 1.00 D (95% CI 0.93 to 1.07), 0.31 D (95% CI 0.17 to 0.44), and 0.34 (95% CI 0.08 to 0.60), respectively (moderate-certainty evidence). Axial elongation was less for children treated with atropine (MD -0.35 mm, 95% CI -0.38 to -0.31; n = 502) and pirenzepine (MD -0.13 mm, 95% CI -0.14 to -0.12; n = 326) than for those treated with placebo (moderate-certainty evidence) in two studies. Another study showed favorable results for three different doses of atropine eye drops compared with tropicamide eye drops (MD 0.78 D, 95% CI 0.49 to 1.07 for 0.1% atropine; MD 0.81 D, 95% CI 0.57 to 1.05 for 0.25% atropine; and MD 1.01 D, 95% CI 0.74 to 1.28 for 0.5% atropine; n = 196; low-certainty evidence) but did not report axial length. Systemic 7-methylxanthine had little to no effect on myopic progression (MD 0.07 D, 95% CI -0.09 to 0.24) nor on axial elongation (MD -0.03 mm, 95% CI -0.10 to 0.03) compared with placebo in one study (n = 77; moderate-certainty evidence). One study did not find slowed myopia progression when comparing timolol eye drops with no drops (MD -0.05 D, 95% CI -0.21 to 0.11; n = 95; low-certainty evidence). Combinations of interventions: two studies found that children treated with atropine plus multifocal spectacles progressed 0.78 D (95% CI 0.54 to 1.02) less than children treated with placebo plus SVLs (n = 191; moderate-certainty evidence). One study reported -0.37 mm (95% CI -0.47 to -0.27) axial elongation for atropine and multifocal spectacles when compared with placebo plus SVLs (n = 127; moderate-certainty evidence). Compared with children treated with cyclopentolate plus SVLs, those treated with atropine plus multifocal spectacles progressed 0.36 D less (95% CI 0.11 to 0.61; n = 64; moderate-certainty evidence). Bifocal spectacles showed small or negligible effect compared with SVLs plus timolol drops in one study (MD 0.19 D, 95% CI 0.06 to 0.32; n = 97; moderate-certainty evidence). One study comparing tropicamide plus bifocal spectacles versus SVLs reported no statistically significant differences between groups without quantitative results. No serious adverse events were reported across all interventions. Participants receiving antimuscarinic topical medications were more likely to experience accommodation difficulties (Risk Ratio [RR] 9.05, 95% CI 4.09 to 20.01) and papillae and follicles (RR 3.22, 95% CI 2.11 to 4.90) than participants receiving placebo (n=387; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Antimuscarinic topical medication is effective in slowing myopia progression in children. Multifocal lenses, either spectacles or contact lenses, may also confer a small benefit. Orthokeratology contact lenses, although not intended to modify refractive error, were more effective than SVLs in slowing axial elongation. We found only low or very low-certainty evidence to support RGPCLs and sperical aberration SCLs.

Association between long-term orthokeratology responses and corneal biomechanics

Myopia is very prevalent worldwide, especially among Asian populations. Orthokeratology is a proven intervention to reduce myopia progression. The current study investigated association between baseline corneal biomechanics and orthokeratology responses, and changes of corneal biomechanics from long-term orthokeratology. We fitted 59 adult subjects having myopia between −4.00D to −5.00D with overnight orthokeratology. Corneal biomechanics was measured through dynamic bidirectional corneal applanation (in terms of corneal hysteresis, CH and corneal resistance factor, CRF) and corneal indentation (in terms of corneal stiffness, S and tangent modulus, E). Subjects with poor orthokeratology responses had lower E (mean 0.474 MPa) than subjects with good orthokeratology responses (mean 0.536 MPa). Successful orthokeratology for 6 months resulted in reducing CH (reduced by 5.8%) and CRF (reduced by 8.7%). Corneal stiffness was stable, but E showed an increasing trend. Among subjects with successful orthokeratology, a higher baseline S resulted in greater myopia reduction (Pearson correlation coefficient, r = 0.381, p = 0.02).

Combined Atropine with Orthokeratology for Myopia Control: Study Design and Preliminary Results

Purpose: The purpose of this study is to present the study design and one month's preliminary results of a 2-year randomized trial, Combined Atropine with Orthokeratology (AOK), for myopia control study. Methods: Children aged 6 to <11 years and with 1.00-4.00 D myopia were randomly assigned to AOK group or ortho-k alone (OK) group. Subjects are required to attend routine ortho-k aftercare visits (first-overnight, 1 week, 2 weeks, 3 weeks, 1 month, and every 3 months after commencement of lens wear). Clinical outcomes, including lens performance, changes in refractive error, unaided vision, ocular adverse events, corneal staining, lens binding and centration, and axial length, are also assessed at 6-monthly data collection visit. Results: Data of 30 AOK and 34 OK subjects who had completed the 1-month visit were analyzed. No significant differences in baseline data were found between the two groups (P > 0.05). At the 1-month visit, first-fit success rate was 95%, with full myopia reduction. Mild corneal staining was observed in 23.3% and 30.9% and mild self-reported lens binding in 50% and 41% in AOK and OK groups, respectively, after 1-month lens wear. Mean (±standard deviation) change in axial length was significantly higher in AOK than OK subjects (AOK: -0.05 ± 0.05 mm; OK: -0.02 ± 0.03 mm) (P = 0.003). Conclusions: After 1 month of treatment, first-fit success rate of ortho-k lenses was high in both groups of subjects; addition of 0.01% atropine in AOK subjects did not affect the lens performance or clinical responses. These results provide the assurance that it is acceptable to continue this longitudinal study, as longer study duration, usually 2 years, is required to determine the effectiveness of treatment for myopia control.

Efficacy of Trial Fitting and Software Fitting for Orthokeratology Lens: One-Year Follow-Up Study

OBJECTIVE

To observe and compare the clinical efficacy of 1-year trial fitting and software fitting orthokeratology lenses.

METHODS

One hundred myopes who received vision correction with the use of orthokeratology lenses form July 2016 to September 2017 were included in this study. Subjects were assigned randomly into the two groups: the trial fitting group (group A) and the software fitting group (group B). For the right eye of each subject, measurements, such as uncorrected visual acuity (UCVA, logarithm of minimal angle of resolution), refractive error, corneal topography, ocular health status, and the fitting situation, were obtained at baseline, 1 week, 1 month, 3 months, 6 months, and 12 months after lens wear. Axial length and corneal endothelium cells (CECs) were also measured at baseline and 12 months after wearing the lens.

RESULTS

Compared with the baseline, the spherical equivalent refraction, UCVA, and central corneal curvature changed significantly after orthokeratology (OK) lens wear (all P<0.05). Between groups A and B, the parameters aforementioned were insignificant at each time point (all P>0.05). Axial length and CECs showed no significant changes during the first year of OK treatment (all P>0.05). Rate of corneal staining between two groups revealed no difference during 1-year visit (P<0.05).

CONCLUSION

Both the trial lens fitting and software fitting approaches were effective in temporarily reducing myopia, providing good UCVA and delaying the elongation of axial length for moderate and high myopic adolescents. Both the two approaches can be combined in OK lens fitting.

Vision Improvement and Compliance With the Use of Orthokeratology Lenses in School Children: A Sample From Five Primary Schools in Northern Taiwan

PURPOSE

To assess the visual acuity and compliance with the use of orthokeratology lenses (OrthoK) in school children.

METHODS

A retrospective study was conducted to determine the education-related factors influencing the improvement in visual acuity in myopic students using OrthoK in five primary schools in Taiwan.

RESULTS

Of the 5,173 eligible students from five primary schools, 1906 (36.8%) students were diagnosed with myopia. Among 201 (10.6%) students wearing OrthoK, 69.7% had used them for at least 1 year, 53.2% achieved visual acuity greater than 0.8 (6/7.5, log of minimal angle of resolution 0.1) in school, and 49.8% had received health education related to OrthoK care. Multiple logistic regression analysis showed that a higher possibility to achieve visual acuity greater than 0.8 was associated with more than 1-year use of OrthoK, good compliance, and receiving health education from an ophthalmologist.

CONCLUSION

It is important that children wearing OrthoK receive education and comply with the use of OrthoK for visual acuity improvement.

Influence of Overnight Orthokeratology on Corneal Surface Shape and Optical Quality

Purpose

To investigate the changes of corneal surface shape and optical quality during orthokeratology.

Methods

49 eyes of 26 patients (10.63 ± 2.02 years old) who underwent overnight orthokeratology for myopia were prospectively examined. The corneal surface shape parameters, including surface regularity index (SRI) and surface asymmetry index (SAI), were attained with an OPD-III SCAN. The higher-order aberrations and higher-order Strehl ratios were calculated under a 3 mm pupil diameter before orthokeratology, 1 month, 3 months, and 6 months after orthokeratology. A P value of less than 0.05 was statistically significant.

Results

Months after orthokeratology, SRI and SAI were both showing a significant increase in comparison with those before orthokeratology (P < 0.001). After orthokeratology, for a 3 mm pupil, the higher-order Strehl ratio presented a reduction of 0.217 μm (P < 0.001), and the higher-order aberration root mean square (HOA RMS) showed a mean increase of 0.100 μm (P < 0.001). There were significant increases in spherical aberration (P < 0.001) and coma (P = 0.044) after orthokeratology. Trefoil showed a slight reduction at month 6 after orthokeratology, but there was no statistical significance (P = 0.722).

Conclusion

Overnight orthokeratology for a correction of myopia resulted in a significant improvement in refractive error but increased corneal irregularity and ocular higher-order aberrations, especially in spherical aberration.

The control effect of orthokeratology on axial length elongation in Chinese children with myopia

BACKGROUND

To retrospectively compare axial elongation in children with different degrees of myopia wearing spectacles and undergoing ortho-k treatment.

METHODS

The medical records of 128 patients who were fitted with spectacles or orthokeratology (ortho-k) lenses in our clinic between 2008 and 2009 were reviewed. Ortho-k group comprised 65 subjects and 63 subjects wearing spectacles were included in the control group. Subjects were also divided into low-myopia, moderate-myopia and high-myopia groups, based on the basic spherical equivalent refractive error. Axial length periodically measured over 2-year of lens wear and changes in axial length were compared between treatment groups and between subgroups with different degrees of myopia.

RESULTS

The control group exhibited more changes in axial length than the ortho-k group at both 12 months (0.39 ± 0.21 mm vs 0.16 ± 0.17 mm, p <0.001) and 24 months (0.70 ± 0.35 mm vs 0.34 ± 0.29 mm, p <0.001). Axial length elongation was estimated to be slower by about 51% in the ortho-k group. Similar results were found for the subgroups (49%, 59% and 46% reductions, respectively). In the group with low and moderate myopia, the annual increases in axial length were significantly different between the ortho-k and control groups during both the first ( Low myopia: 0.19 ± 0.17 mm vs 0.40 ± 0.18 mm, p = 0.001; Moderate myopia: 0.14 ± 0.18 mm vs 0.45 ± 0.22 mm, p <0.001) and second ( Low myopia: 0.18 ± 0.14 mm vs 0.32 ± 0.19 mm, p = 0.012; Moderate myopia: 0.18 ± 0.16 mm vs 0.34 ± 0.30 mm, p = 0.030) years. In the high myopia groups, significant differences were only found between the ortho-k and control groups during the first year (0.16 ± 0.18 mm vs 0.34 ± 0.22 mm, p = 0.004). The 2-year axial elongation was significantly associated with initial age (p <0.001) and treatment (p <0.001), but not with gender, initial refractive error, initial axial length, initial corneal curvature.

CONCLUSIONS

This 2-year study indicates that ortho-k contact lens wear is effective for reducing myopia progression in children with low, moderate and high myopia.