Additive effect of atropine eye drops and short-term retinal defocus on choroidal thickness in children with myopia

Effect of childhood atropine treatment on adult choroidal thickness using sequential deep learning-enabled segmentation

PURPOSE

To describe choroidal thickness measurements using a sequential deep learning segmentation in adults who received childhood atropine treatment for myopia control.

DESIGN

Prospective, observational study.

METHODS

Choroidal thickness was measured by swept-source optical coherence tomography in adults who received childhood atropine, segmented using a sequential deep learning approach.

RESULTS

Of 422 eyes, 94 (22.3 %) had no previous exposure to atropine treatment, while 328 (77.7 %) had received topical atropine during childhood. After adjusting for age, sex, and axial length, childhood atropine exposure was associated with a thicker choroid by 32.1 μm (95 % CI, 9.2-55.0; P = 0.006) in the inner inferior, 23.5 μm (95 % CI, 1.9-45.1; P = 0.03) in the outer inferior, 21.8 μm (95 % CI, 0.76-42.9; P = 0.04) in the inner nasal, and 21.8 μm (95 % CI, 2.6-41.0; P = 0.03) in the outer nasal. Multivariable analysis, adjusted for age, sex, atropine use, and axial length, showed an independent association between central subfield choroidal thickness and the incidence of tessellated fundus (P < 0.001; OR, 0.97; 95 % CI, 0.96-0.98).

CONCLUSIONS

This study demonstrated that short-term (2-4 years) atropine treatment during childhood was associated with an increase in choroidal thickness of 20-40 μm in adulthood (10-20 years later), after adjusting for age, sex, and axial length. We also observed an independent association between eyes with thicker central choroidal measurements and reduced incidence of tessellated fundus. Our study suggests that childhood exposure to atropine treatment may affect choroidal thickness in adulthood.

Choroidal Changes During and After Discontinuing Long-Term 0.01% Atropine Treatment for Myopia Control

Purpose

Few studies have explored choroidal changes after cessation of myopia control. This study evaluated the choroidal thickness (ChT) and choroidal vascularity index (CVI) during and after discontinuing long-term low-concentration atropine eye drops use for myopia control.

Methods

Children with progressive myopia (6-16 years; n = 153) were randomized to receive 0.01% atropine eye drops or a placebo (2:1 ratio) instilled daily over 2 years, followed by a 1-year washout (no eye drop use). Optical coherence tomography imaging of the choroid was conducted at the baseline, 2-year (end of treatment phase), and 3-year (end of washout phase) visits. The main outcome measure was the subfoveal ChT. Secondary measures include the CVI.

Results

During the treatment phase, the subfoveal choroids in both treatment and control groups thickened by 12-14 µm (group difference P = 0.56). During the washout phase, the subfoveal choroids in the placebo group continued to thicken by 6.6 µm (95% confidence interval [CI] = 1.7 to 11.6), but those in the atropine group did not change (estimate = -0.04 µm; 95% CI = -3.2 to 3.1). Participants with good axial eye growth control had greater choroidal thickening than the fast-progressors during the treatment phase regardless of the treatment group (P < 0.001), but choroidal thickening in the atropine group's fast-progressors was not sustained after stopping eye drops. CVI decreased in both groups during the treatment phase, but increased in the placebo group after treatment cessation.

Conclusions

On average, compared to placebo, 0.01% atropine eye drop treatment did not cause a differential rate of change in ChT during treatment, but abrupt cessation of long-term 0.01% atropine eye drops may disrupt normal choroidal thickening in children.

Response of the human choroid to short-term changes in eyelid and periocular temperature

CLINICAL RELEVANCE

Choroidal thickness measurement is gaining popularity in clinical practice and research as an early indicator of myopia progression. Understanding the influence of temperature on choroidal thickness changes will improve the reliability of the measures.

BACKGROUND

It has been suggested that environmental temperature may affect choroidal thickness and blood flow, with potential implications for ocular disease and refractive development. This study investigates the effect of changes in eyelid/ocular adnexa temperature on choroidal thickness.

METHODS

In a paired-eye study, 20 young, healthy subjects received a warm stimulus (heat pack) over one closed eye and simultaneously a cold stimulus (ice pack) over the other for 10 min. Eyelid temperatures were monitored with thermal probes, and optical coherence tomography scans of the retina and choroid were taken before and after heating and cooling, and then every 5 min during a 15-min recovery period. Retinal and choroidal thicknesses were measured across the macular region (6 mm), including the subfoveal (1 mm), parafoveal (1-3 mm), and perifoveal (3-5 mm) regions, and compared between the cooled and warmed eyes.

RESULTS

When the thermal stimuli were applied, eyelid surface temperatures changed predictably and remained significantly different (by approximately 10-15°C) between the eyes after 2 min (p < .001). Relative to the warmed eye, macular choroidal thickness in the cooled eye increased significantly after 10 min of treatment (p = .004). This choroidal thickening response occurred in the subfoveal, parafoveal, and perifoveal regions (all p < .05). Upon removal of the thermal stimuli, choroidal thickness rapidly returned to the baseline and was no longer different between the cooled and warmed eye (p = .641).

CONCLUSION

Cooling the anterior eye by application of a cold stimulus directly onto the closed eyelid caused a small but significant increase in choroidal thickness relative to warming the anterior eye, demonstrating that the choroid can modulate its thickness rapidly and transiently in response to local temperature changes.

Comparison of Changes in Retinal Vascular Density and Thickness After Using Low-Level Red Light and 0.01% Atropine in Premyopic Children

Purpose

To compare changes in superficial retinal vascular density (SRVD), deep retinal vascular density (DRVD), and retinal thickness (RT) of the macular zone after repeated low-level red light (RLRL) and 0.01% atropine exposure in premyopic schoolchildren.

Methods

Prospective randomized trial. Sixty-nine schoolchildren with cycloplegic refraction >-0.75 D and ≤0.50 D were randomly assigned to RLRL and 0.01% atropine groups. SRVD, DRVD, and RT were measured using swept-source optical coherence tomography at baseline and six months. The macular zone was divided into three concentric rings (fovea, parafovea, and perifovea) using the Early Treatment Diabetic Retinopathy Study.

Results

After six months, the whole, parafoveal, and perifoveal SRVD significantly increased in the two groups (all P < 0.05). Multivariate regression analyses showed that none of these changes varied significantly between the two groups (all P > 0.05), whereas foveal SRVD remained stable in both groups (all P > 0.05). In the RLRL group, the whole and perifoveal DRVD increased significantly (all P < 0.05), whereas no statistical difference was observed in the foveal and parafoveal DRVD. DRVD remained stable in the 0.01% atropine group (all P > 0.05). No significant differences were observed in RT changes between the two groups (all P > 0.05). In comparison, there were no significant changes in SRVD, DRVD, or RT after six months in the placebo group in our previous study.

Conclusions

SRVD increased similarly in the RLRL and 0.01% atropine groups, whereas DRVD increased only in the former group. There were no significant RT changes in either group after six months of treatment in premyopic schoolchildren.

Translational Relevance

This research observed the effects of low-level red light and 0.01% atropine on retinal vasculature, offering valuable insights into myopia progression prevention.

Myopia Is an Ischemic Eye Condition: A Review from the Perspective of Choroidal Blood Flow

Myopia is a common refractive error that affects a large proportion of the population. Recent studies have revealed that alterations in choroidal thickness (ChT) and choroidal blood flow (ChBF) play important roles in the progression of myopia. Reduced ChBF could affect scleral cellular matrix remodeling, which leads to axial elongation and further myopia progression. As ChT and ChBF could be used as potential biomarkers for the progression of myopia, several recent myopia treatments have targeted alterations in ChT and ChBF. Our review provides a comprehensive overview of the recent literature review on the relationship between ChBF and myopia. We also highlight the importance of ChT and ChBF in the progression of myopia and the potential of ChT as an important biomarker for myopia progression. This summary has significant implications for the development of novel strategies for preventing and treating myopia.

Effect of spectacle lenses with aspherical lenslets on choroidal thickness in myopic children: a 3-year follow-up study

BACKGROUND

To investigate the impact of wearing spectacle lenses with highly aspherical lenslets (HAL) for 3 years and the impact of switching from single-vision lenses (SVL) to HAL on choroidal thickness (ChT).

METHODS

Fifty-one participants who had already worn HAL for 2 years continued wearing them for an additional year (HAL group). Further, 50 and 41 participants who had worn spectacle lenses with slightly aspherical lenslets (SAL) and SVL for 2 years, respectively, switched to wearing HAL for another year (SAL-HAL and SVL-HAL groups). Additionally, 48 new participants aged 10-15 years were enrolled to wear SVL at the third year (new-SVL group). ChT was measured every 6 months throughout the study.

RESULTS

Significant differences were observed in the changes in ChT among the four groups at the third year (all P < 0.05 except for the outer nasal region: P = 0.09), with the new-SVL group showing larger reductions compared with the other three groups. However, none of the three HAL-wearing groups showed significant changes in ChT at the third year (all P > 0.05). When comparing the changes in ChT for 3 years among the HAL, SAL-HAL, and SVL-HAL groups, significant differences were found before switching to HAL, but these differences were abolished after all participants switched to HAL.

CONCLUSIONS

Compared to those in the SVL group, choroid thinning was significantly inhibited in all the HAL groups. Wearing HAL for 3 years no longer had a choroidal thickening effect but could still inhibit choroidal thinning compared to wearing SVL.

TRIAL REGISTRATION

The study was registered at the Chinese Clinical Trial Registry (ChiCTR1800017683), http://www.chictr.org.cn/showproj.aspx?proj=29789 .

Low concentration atropine and myopia: a narrative review of the evidence for United Kingdom based practitioners

The prevalence of myopia is increasing across the world. Controlling myopia progression would be beneficial to reduce adverse outcomes such as retinal detachment and myopic maculopathy which are associated with increased axial length. Pharmacological control of myopia progression with atropine has been investigated since the 19th century and the benefits of slowing myopia progression are considered against the side-effects of near blur and photophobia. More recently, randomised trials have focused on determining the optimum concentration of atropine leading to low-concentration atropine being used to manage myopia progression by practitioners across the world. Currently, in the United Kingdom, there is no licensed pharmacological intervention for myopia management. The aim of this review is to interpret the available data to inform clinical practice. We conducted a narrative review of the literature and identified peer-reviewed randomised controlled trials using the search terms 'myopia' and 'atropine', limited to the English language. We identified two key studies, which were the Atropine in the Treatment Of Myopia (ATOM) and Low-concentration Atropine for Myopia Progression (LAMP). Further studies were identified using the above search terms and the references from the identified literature. Atropine 0.01% has a modest effect on controlling axial length progression. Atropine 0.05% appears to be superior to atropine 0.01% in managing myopia progression. There is a dose-dependent rebound effect when treatment is stopped. Atropine is a well-tolerated, safe, and effective intervention. Treatment would be needed for several years and into adolescence, until axial length progression is stable.

The effect of topical 1 % atropine on ocular dimensions and diurnal rhythms of the human eye

The effect of topical 1 % atropine on the diurnal rhythms of the human eye was investigated. Participants wore an activity monitor on Days 1-7. A set of measures (epochs) encompassing intraocular pressure (IOP), ocular biometry, and retinal imaging were obtained on Day 7 (baseline), followed by eight epochs on Day 8, and one on Day 9 from both eyes of healthy participants (n = 22, 19-25 years). The sleep time of participants (collected via actigraphy) was used as a reference in scheduling epochs. Topical 1 % atropine was instilled in the dominant eye on Day 8, 2 h after habitual wake time, using the fellow eye as control (paired-eye design). Sinusoids with a 24-h period were fitted to the data, and a non-linear mixed-effects model was used to estimate rhythmic statistics. There were no interocular differences in any of the measured parameters at baseline. Comparing pre- versus post-atropine in treated eyes revealed lower IOP, deeper anterior chamber (ACD), decreased crystalline lens thickness and shorter axial length (AL). The same trends were observed when comparing atropine-treated versus fellow control eyes, except for IOP and AL (no differences). Both atropine-treated and fellow control eyes showed significant diurnal variations in all ocular parameters, with atropine-treated eyes revealing larger AL and retinal thickness amplitudes, smaller vitreous chamber depth (VCD) amplitudes, and a significant phase advancement for ACD and VCD. There were no interocular differences in choroidal thickness rhythms. In conclusion, while ocular diurnal rhythms persisted after instillation of 1 % atropine, many rhythmic parameters were altered.

Efficacy of Repeated Low-Level Red-Light Therapy for Slowing the Progression of Childhood Myopia: A Systematic Review and Meta-analysis

PURPOSE

To evaluate the long-term efficacy and safety of repeated low-intensity red light (RLRL) treatment for childhood myopia.

DESIGN

Systematic review and meta-analysis METHODS: We searched PubMed, Web of Science, CNKI, and Wanfang from inception to February 8, 2023. We used the RoB 2.0 and ROBINS-I tools to assess the risk of bias and then used a random-effect model to calculate the weighted mean difference (WMD) and 95% CIs. The primary outcomes were WMD in spherical equivalent refractive error (SER), WMD in axial length (AL), and WMD in subfoveal choroid thickness (SFChT). Subgroup analyses were performed to investigate the sources of heterogeneity based on variation in follow-up and study design. The Egger and Begg tests were used to assess publication bias. Sensitivity analysis was used to verify the stability.

RESULTS

This analysis included 13 studies (8 randomized controlled trials, 3 non-randomized controlled trials, and 2 cohort studies) involving 1857 children and adolescents. Eight studies met the meta-analysis criteria, and the WMD for myopia progression between RLRL and the control group was 0.68 diopters (D) per 6 months (95% CI = 0.38 to 0.97 D; I2 = 97.7%; P < .001) for SER change; -0.35 mm per 6 months (95% CI = -0.51 to -0.19 mm; I2 = 98.0%; P < .001) for AL elongation; and 36.04 µm per 6 months (95% CI = 19.61 to 52.48 µm; I2 = 89.6%; P < .001) for SFChT change.

CONCLUSIONS

Our meta-analysis shows that RLRL therapy may be effective for delaying the progression of myopia. The evidence is low certainty, and larger and better randomized clinical trials with 2-year follow-ups are needed to improve the existing state of knowledge to inform medical guidelines more comprehensively.

Combined 0.01% atropine with orthokeratology in childhood myopia control (AOK) study: A 2-year randomized clinical trial

BACKGROUND

To investigate whether combining 0.01% atropine with orthokeratology (AOK) has a better effect in retarding axial elongation, compared with orthokeratology alone (OK) over two years.

METHODS

A total of 96 Chinese children aged six to < 11 years with myopia (1.00 - 4.00 D, inclusive) were randomized into either the AOK or OK group in a 1:1 ratio. Axial length (the primary outcome), and secondary outcomes (e.g. pupil size and choroidal thickness) were measured at 1-month and at 6-monthly intervals after commencement of treatment.

RESULTS

Both intention-to-treat and per-protocol analyses showed significantly slower axial elongation in the AOK group than OK group over two years (P = 0.008, P < 0.001, respectively). AOK subjects had statistically slower axial elongation (adjusted mean [standard error], 0.17 [0.03] mm vs 0.34 [0.03] mm, P < 0.001), larger increase in mesopic (0.70 [0.09] mm vs 0.31 [0.09] mm, P = 0.003) and photopic pupil size (0.78 [0.07] mm vs 0.23 [0.07] mm, P < 0.001), and greater thickening of the choroid (22.6 [3.5] µm vs -9.0 [3.5] µm, P < 0.001) than OK subjects over two years. Except for a higher incidence of photophobia in the AOK group (P = 0.006), there were no differences in the incidence of any other symptom or adverse events between the two groups. Slower axial elongation was associated with a larger increase in the photopic pupil size and a greater thickening in the choroid in the AOK group.

CONCLUSIONS

Slower axial elongation following 2-year AOK treatment may result from increased pupil dilation and a thickening in the choroid observed in the AOK group.

Changes of Choroidal Thickness in Children after Short-Term Application of 1% Atropine Gel

INTRODUCTION

The aim of the study was to assess changes in choroidal thickness (ChT) after administration of 1% atropine for 1 week in myopic, emmetropic, and hyperopic children.

METHODS

A total of 235 children aged 4-8 years, which included 46 myopia, 34 emmetropia, and 155 hyperopia patients, were recruited and divided into three groups according to the spherical equivalent with the use of 1% atropine twice a day for 1 week. The ChT was measured at baseline and 1 week.

RESULTS

In the myopia and emmetropia groups, following administration of 1% atropine gel, the ChT thickened significantly under the fovea (i.e., from 278.29 ± 53.01 μm to 308.24 ± 57.3 μm, p < 0.05; from 336.10 ± 78.60 μm to 353.46 ± 70.22 μm, p < 0.05, respectively), and at all intervals from the fovea, while in the hyperopia group, there was no significant difference in the ChT except the nasal side (p < 0.05).

CONCLUSION

Topical administration of 1% atropine gel for 1 week significantly increased the subfoveal and parafoveal ChT in children with myopia and emmetropia. Atropine did not increase the ChT in hyperopic children, except on the nasal side.

Short-term effect of orthokeratology lens wear on choroidal blood flow in children with low and moderate myopia

We investigated changes in choroidal vascularity and choriocapillaris blood perfusion during orthokeratology (Ortho-K) lens wear. Sixty-two children with low to moderate myopia were enrolled. The Ortho-K group (n = 42) continuously wore Ortho-K lenses for 3 months, and the controls (n = 20) wore single-vision distance spectacles. All of the patients were instructed to return for follow-up visits after 1 day, 1 week and 1 month and 3 months of treatment. The subfoveal choroidal thickness (SFChT), choroidal vascularity [including the total choroidal area, luminal area, stromal area, and choroidal vascularity index (CVI)] and percentage of choriocapillaris flow voids (FV%) were determined with a Cirrus HD-OCT instrument. Additionally, ocular parameters were measured. In the Ortho-K group, the SFChT significantly increased by 12.61 ± 5.90 μm, the CVI was significantly increased by 2.99 ± 2.07% and 3.01 ± 2.32% on the horizontal and vertical scans respectively, and the FV% was significantly decreased by 0.89 ± 0.34% from baseline at the 1-week visit (all p < 0.001). The choroidal parameters remained unchanged at the 1-month and 3-month follow-ups with respect to the 1-week follow-up. In the control group, the choroidal parameters did not change significantly at 1 month (all p > 0.05). At the 3-month visit, the changes in the axial length (AL) and vitreous chamber depth (VCD) were significantly greater in the control group than in the Ortho-K group (0.14 ± 0.23 and 0.03 ± 0.05 mm in AL, 0.15 ± 0.23 and 0.06 ± 0.03 mm in VCD respectively). Our longitudinal study showed several choroidal parameter changes in the early stage in Ortho-K lens wearers with low to moderate myopia, and these changes persisted over 3 months. We speculate that Ortho-K lenses regulate choroidal thickness and blood perfusion, affecting myopia development.

Changes in the Choroidal Thickness of Children Wearing MiSight to Control Myopia

Background: Due to the importance of choroidal thickness in the development of myopia, this study examined the effect of MiSight contact lenses (CLs) on the choroidal thickness of myopic children and the differences between responders and non-responders to the treatment with these CLs. Methods: A total of 41 myopic children were fitted with MiSight CLs and 33 with single-vision spectacles. They were followed up for two years. Subfoveal choroidal thickness and choroidal thickness 1 and 3 mm temporal and nasal to the fovea were measured by OCT at baseline and one and two years after the treatment. Differences in all the choroidal thickness parameters were assessed in each group over time. Patients from the MiSight group were classified based on a specific range of changes in axial length at the end of the second year of treatment as “responders” (AL change < 0.22 mm/per year) and “non-responders”, and the choroidal thickness of both groups was analyzed. Results: The subfoveal choroidal thickness of the MiSight and single-vision spectacle groups did not show any changes over time. Wearing MiSight CLs induced relative choroidal thickening in the responder group in the first year of treatment. Conclusion: Choroidal thickness might work as a predictor of the effectiveness of MiSight in myopia treatment.

Daily or Less Frequent Topical 1% Atropine Slows Defocus-Induced Myopia Progression in Contact Lens-Wearing Guinea Pigs

Purpose

This study compared the efficacy of topical 1% atropine applied daily versus every 3 days for controlling myopia progression in guinea pigs.

Methods

To induce myopia, pigmented guinea pigs (New Zealand strain, n = 38) wore monocular −10 D rigid gas-permeable (RGP) contact lenses, which were replaced after 3 weeks with −15 diopter (D) contact lenses. Animals were treated with 1% atropine either daily (Atr-QD; n = 12), or every 3 days (Atr-Q3D; n = 11), or with artificial tears (control group; n = 15). Spherical equivalent refractive error (SER) and axial length (AL) data, as well as retinal and choroidal thickness data were collected weekly.

Results

Whereas mean (±SEM) interocular differences (treated - fellow) in both SER and AL at week 0 (baseline) were similar for all groups, significant differences between the atropine-treated and control groups were evident by week 6 (SER and AL, P < 0.001). The treated eyes of the control group showed relatively more axial elongation and myopia progression than both the Atr-QD and Atr-Q3D groups. Choroidal blood vessel area also decreased over time in the treated eyes of the control group, coupled with choroidal thinning overall, with these changes being attenuated by atropine. Retinal thickness showed a developmental decrease over the treatment period but was unaffected by atropine.

Conclusions

For this defocus-induced guinea pig model of myopia, application of 1% topical atropine slows myopia progression, even when applied every 3 days.

Translational Relevance

The results from this study suggest that the frequency of dosing for topical atropine may be reduced from the widely used daily dosing regimen without loss of myopia control efficacy.

Effect of 0.01% Atropine on Accommodation in Myopic Teenagers

Purpose: The purpose of the study is to evaluate the effects of 0.01% atropine eye drops on accommodative system parameters among teenagers with low myopia. Methods: Ninety-five myopic teenagers [39 boys (8.69 ± 2.473) and 56 girls (8.54 ± 2.054) aged 5-17 years] with no history of eye disease were enrolled. Biometric and accommodative system parameters were evaluated before and at 1 week, 1 month, 3 months, and 6 months of 0.01% atropine eye drop instillation. Results: Participants without accommodative demand at 6 months demonstrated insignificant changes after the atropine instillation (all p > 0.05). Nevertheless, there were significant differences in accommodative sensitivity, accommodative amplitude, accommodative responsiveness, and negative relative accommodation (NRA) at 3 months compared with baseline after atropine instillation (all p < 0.05). Except spherical equivalent refraction, cornea thickness, intraocular pressure, and axial length were stable after the 0.01% atropine instillation (all p > 0.05). Conclusion: Morphologically, current measurements suggested that 0.01% atropine had favorable reduction of accommodation for childhood low myopia over a half-year period.

Short-Term Effects of Atropine 0.01% on the Structure and Vasculature of the Choroid and Retina in Myopic Chinese Children

Introduction

To explore the short-term effects of atropine 0.01% on the structure and vasculature of the choroid and retina in myopic Chinese children.

Methods

This study was a single-center randomized clinical trial. A total of 40 subjects with myopia < − 6.0 D were enrolled and randomized to receive atropine 0.01% once nightly with regular single-vision lenses or to simply wear regular single-vision lenses at an allocation ratio of 1:1. Follow-up visits were planned at 1 month and 3 months. Choroidal thickness (ChT) was obtained by optical coherence tomography (OCT). Retinal vessel density (RVD), retinal thickness (RT), foveal avascular zone (FAZ) and choriocapillaris flow (CCF) were measured by optical coherence tomography angiography (OCTA). The RVD and RT were measured at fovea, parafovea and perifovea area and four quadrants.

Results

Twenty-one subjects were allocated into the atropine group and 19 subjects into the control group. Over 3 months, the control group showed greater progression of myopia than those in the atropine group. ChT in the atropine group increased 11.12 ± 13.96 μm, which was not significant compared with that of the control group. None of the retinal sectors in atropine-treated eyes showed significant changes of RT and RVD compared with the control group. Besides, FAZ and CCF of the atropine group were not affected by atropine use over time, and there was no difference between the two groups.

Conclusion

Administration of atropine 0.01% eye drops demonstrated no effect on RVD, FAZ and CCF over 3 months, while a modest increase of ChT was observed in atropine-treated eyes.

Trial Registration Number

ChiCTR1800017154.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40123-022-00476-0.

Efficacy of combined orthokeratology and 0.01% atropine for myopia control: the study protocol for a randomized, controlled, double-blind, and multicenter trial

BACKGROUND

The prevalence of myopia is increasing worldwide and is presently recognized as a major public health issue. Researchers and clinicians have been devoted in exploring appropriate clinical interventions to slow its progression in children. Mounting publications have proven that both orthokeratology (OK lens) and 0.01% atropine eyedrop can retard eye growth and myopia progression. However, it remains unclear whether the combination of OK lens and 0.01% atropine has the potential to magnify the effectiveness of myopia control. The present study aims to compare the myopia control efficiency of the combination of OK lens and 0.01% atropine with the monotherapy of OK lens in children.

METHODS

The present study is a randomized, controlled, double-blind and multicenter clinical trial. A total of 96 children within 8-12 years old were recruited. These participants are treated with the combination of OK lens and 0.01% atropine eyedrop or the combination of OK lens and placebo eyedrop. Each group includes 48 participants. The inclusion criteria are as follows: myopia between - 1.00 and - 4.00 D in either eye and astigmatism of no more than 1.50 D. The follow-up time points will be 1, 6, 12, 18, and 24 months from randomization. The primary outcome is determined by the difference in axial length of the two groups, between the baseline and 24 months from randomization.

DISCUSSION

The present randomized, controlled clinical trial would indicate the additive effects of the combination of OK lens and 0.01% atropine, and the extent of these effects, in retarding myopia progression and axial elongation in children.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR), ChiCTR1800018419 . Registered on 17 September 2018. http://www.chictr.org.cn/showproj.aspx?proj=29216.

Emmetropic, But Not Myopic Human Eyes Distinguish Positive Defocus From Calculated Blur

Purpose

Defocus blur imposed by positive lenses can induce hyperopia, whereas blur imposed by diffusers induces deprivation myopia. It is unclear whether the retina can distinguish between both conditions when the magnitude of blur is matched.

Methods

Ten emmetropic (average 0.0 ± 0.3 diopters [D]) and 10 subjects with myopia (−2.7 ± 0.9 D; 24 ± 4 years) watched a movie on a large screen (65 inches at 2 meters (m) distance. The movie was presented either unfiltered (“control”), with calculated low-pass filtering equivalent to a defocus of 2.5 D, or with binocular real optical defocus of +2.5 D. Spatial filtering was done in real-time by software written in Visual C++. Axial length was followed with the Lenstar LS-900 with autopositioning system.

Results

Watching unfiltered movies (“control”) caused no changes in axial length. In emmetropes, watching movies with calculated defocus caused axial eye elongation (+9.8 ± 7.6 µm) while watching movies with real positive defocus caused shorter eyes (−8.8 ± 9.2 µm; difference between both P < 0.0001). In addition, in myopes, calculated defocus caused longer eyes (+8.4 ± 9.0 µm, P = 0.001). Strikingly, myopic eyes became also longer with positive defocus (+9.1 ± 11.2 µm, P = 0.02). The difference between emmetropic and myopic eyes was highly significant (−8.8 ± 9.2 µm vs. +9.1 ± 11.2 µm, respectively, P = 0.001).

Conclusions

(1) In emmetropic human subjects, the retina is able to distinguish between real positive defocus and calculated defocus even when the modulation transfer function was matched, (2) in myopic eyes, the retina no longer distinguishes between both conditions because the eyes became longer in both cases. Results suggest that the retina in a myopic eye has reduced ability to detect positive defocus.

Prevention of Choroidal Thinning by 0.01% Atropine Administered 24 h Before Exposure to Hyperopic Blur in Young Myopes

Purpose: To evaluate the persistence of atropine's effect upon choroidal thickness and ocular biometrics and its interaction with hyperopic blur in a population of young adult myopes. Methods: Twenty young (aged 18-35 years) myopic participants with spherical equivalent refractive error of -0.75 to -6.00 D (mean ± SD -2.85 ± 1.64 D) had subfoveal choroidal thickness (SFCT) measurements derived from scans collected from the right eye only with a SD-OCT instrument (Copernicus SOCT-HR) before, as well as 60 min following the introduction of 3 testing conditions: (1) placebo/hyperopic (-3 D) blur, (2) placebo/hyperopic blur one day after administration of 0.01% atropine, and (3) placebo/no blur. Each combination of blur and pharmacological agent was tested on a separate day at approximately the same time of day between 9 am and 2 pm. Results: Repeated measures ANOVA revealed that hyperopic blur and placebo were associated with a decrease in choroidal thickness (mean change: -10.7 ± 2.7 μm, P < 0.001 after 60 min), whereas administration of 0.01% atropine one day before the introduction of hyperopic blur prevented the thinning of the choroid (mean change of +1.1 ± 3.7 μm after 60 min) compared to baseline (both, P > 0.05). There was also no significant difference between the baseline choroidal thickness measurements for any of the conditions tested. Conclusion: Low dose atropine can inhibit signals associated with hyperopic defocus that cause thinning of the choroid for at least 24 h after initial instillation.

Effects of Single and Repeated Intravitreal Applications of Atropine on Choroidal Thickness in Alert Chickens

INTRODUCTION

Atropine, a muscarinic antagonist, is known since the 19th century to inhibit myopia development in children. One of its effects is that it stimulates choroidal thickening. Thicker choroids, in turn, have been linked to myopia inhibition. We used the atropine-stimulated choroidal response in the chicken to learn more about the time courses and amplitudes of the effects of atropine, as well as whether repeated applications lead to accumulation or desensitization.

METHODS

Intravitreal injections containing 250 µg atropine sulfate were performed in 1 eye around 10:00 in the morning, the fellow eye received vehicle. Chickens with bilateral vehicle injections served as controls. Choroidal thickness was measured over the day for every 2-3 h in alert animals, using spectral domain optical coherence tomography, with 3-5 independent measurements in each eye. Three experiments were done - (1) single injection and time course measured over 1 day, (2) single injection and time course measured over 4 days, and (3) daily injections and time course measured over 4 days for measuring the effects of atropine on vitreal, retinal, and choroidal dopamine, and 3,4-dihydroxyphenylacetic acid levels by using high-performance liquid chromatography with electrochemical detection.

RESULTS

Atropine induced an increase in choroidal thickness by about 60 percent, with a peak amplitude after about 2 h. The effect persisted only for a few hours and had nearly disappeared by evening. Initially, similar amounts of choroidal thickening were observed in vehicle-injected fellow eyes but recovery to baseline was faster. When atropine was injected daily for 4 days, choroids thickened every day with similar amplitudes and time courses, with no signs of either accumulation or desensitization effects. Interestingly, while dopamine release from the retina was stimulated by atropine and followed approximately, the time course of choroidal thickening, its tissue concentration dropped in the choroid.

CONCLUSIONS

Even at relatively high intravitreal doses, effects of atropine on choroidal thickness remained transient, similar to its effects on retinal dopamine. With repeated application every day, the diurnal patterns of choroidal thickening could be reproduced for 4 days with similar amplitudes and time courses. The transient nature of the effects of atropine on the choroid may be relevant for application protocols of atropine against myopia.

Corneal Penetration of Low-Dose Atropine Eye Drops

Major studies demonstrating the inhibition of myopia in children and juveniles by low-dose atropine eye drops provide little information on the manufacturing process and the exact composition of the atropine dilutions. However, corneal penetration might significantly vary depending on preservatives, such as benzalkonium chloride (BAC), and the atropine concentration. Since there is a trade-off between side effects, stability, and optimal effects of atropine on myopia, it is important to gain better knowledge about intraocular atropine concentrations. We performed an ex vivo study to determine corneal penetration for different formulations. Atropine drops (0.01%) of different formulations were obtained from pharmacies and applied to the cornea of freshly enucleated pig eyes. After 10 min, a sample of aqueous humor was taken and atropine concentrations were determined after liquid–liquid extraction followed by high-performance liquid chromatography–tandem mass spectrometry (LC-MS/MS). The variability that originated from variations in applied drop size exceeded the differences between preserved and preservative-free formulations. The atropine concentration in the anterior chamber measured after 10 min was only 3.8 × 10⁻⁸ of its concentration in the applied eye drops, corresponding to 502.4 pM. Obviously, the preservative did not facilitate corneal penetration, at least ex vivo. In the aqueous humor of children’s eyes, similar concentrations, including higher variability, may be expected in the lower therapeutic window of pharmacodynamic action.

Multifocal Orthokeratology versus Conventional Orthokeratology for Myopia Control: A Paired-Eye Study

We conducted a prospective, paired-eye, investigator masked study in 30 children with myopia (-1.25 D to -4.00 D; age 10 to 14 years) to test the efficacy of a novel multifocal orthokeratology (MOK) lens compared to conventional orthokeratology (OK) in slowing axial eye growth. The MOK lens molded a center-distance, multifocal surface onto the anterior cornea, with a concentric treatment zone power of +2.50 D. Children wore an MOK lens in one eye and a conventional OK lens in the fellow eye nightly for 18 months. Eye growth was monitored with non-contact ocular biometry. Over 18 months, MOK-treated eyes showed significantly less axial expansion than OK-treated eyes (axial length change: MOK 0.173 mm less than OK; p < 0.01), and inner axial length (posterior cornea to anterior sclera change: MOK 0.156 mm less than OK, p < 0.01). The reduced elongation was constant across different baseline progression rates (range -0.50 D/year to -2.00 D/year). Visual acuity was less in MOK vs. OK-treated eyes (e.g., at six months, MOK: 0.09 ± 0.01 vs. OK: 0.02 ± 0.01 logMAR; p = 0.01). We conclude that MOK lenses significantly reduce eye growth compared to conventional OK lenses over 18 months.