Study on the Effect of Two Ways of Cycloplegia on Biological Parameters of Ciliary Muscle

Study Overview
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Brief Summary
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Atropine has a ciliary muscle-paralysing effect and causes hyperopic drift. Besides, atropine has been proven to slow the progression of myopia. Many studies have suggested that atropine can increase the thickness of the choroid. However, few studies have discussed changes in the ciliary muscle after treatment with atropine or other cycloplegic agents. This study aimed to assess the difference in ciliary muscle morphology before and after two different cycloplegic agents and to analyze the correlation between the changes of ciliary muscle biological parameters and the changes of eye axis, spherical equivalent, lens diopter, choroidal thickness, etc. One hundred and forty-four children would be randomly assigned 1:1 to the 1% atropine group and the tropicamide group. This study might provide clinical evidence for the role of regulatory factors in the occurrence and development of myopia.

Detailed Description
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The ciliary muscle exhibited an inward-forward contraction during accommodation, resulting in a significant thickening of the anterior area of the ciliary muscle. In addition to ultrasound biomicroscope (UBM), anterior segment optical coherence tomography (AS-OCT) is also commonly used to study morphological changes in the ciliary muscle. Studies using AS-OCT revealed that the posterior area of the ciliary muscle thinned during accommodation. The morphology of the ciliary muscles differs in individuals with refractive errors. Many researchers found that the ciliary muscle became thicker with an increase of axial length (AL) Some studies suggested that myopia primarily affected the posterior area of the ciliary muscle. Atropine has a ciliary muscle-paralysing effect and causes hyperopic drift. Besides, atropine has been proven to slow the progression of myopia. Many studies have suggested that atropine can increase the thickness of the choroid. However, few studies have discussed changes in the ciliary muscle after treatment with atropine or other cycloplegic agents. This study aimed to assess the difference in ciliary muscle morphology before and after two different cycloplegic agents and to analyze the correlation between the changes of ciliary muscle biological parameters and the changes of eye axis, spherical equivalent, lens diopter, choroidal thickness, etc. One hundred and forty-four children would be randomly assigned 1:1 to the 1% atropine group and the tropicamide group. This study might provide clinical evidence for the role of regulatory factors in the occurrence and development of myopia.

Official Title
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Study on the Effect of Two Ways of Cycloplegia on Biological Parameters of Ciliary Muscle

Conditions
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Accomodation, Refractive Errors, Myopia, Cycloplegia

Intervention / Treatment
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* Drug: 1% atropine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ①Age 3 to 12 years old; Astigmatism <2.00D, binocular anisometropia <3.00D, and the best corrected distance visual acuity is at least 0.8, near vision at least 0.8; A clear anterior segment image can be obtained through anterior segment OCT; Have normal thinking and language communication skills, and can actively cooperate with the inspection process; ⑤ No contraindications to atropine treatment such as acute eye inflammation, dry eye, keratoconus, diabetes, etc.; ⑥Written informed consent of the guardian and the child himself Exclusion Criteria: ① Combined with neurological diseases and have allergies or contraindications to cycloplegic drugs or other drugs; Intraocular pressure ≥21mmHg; history of photosensitivity, glaucoma, blue eye syndrome, ocular hypertension, and retinal macular lesions or damage; Patients with chronic eye diseases such as ocular trauma and allergic conjunctivitis; Those who wear contact lenses and those who use myopia control-related drugs within 1 month; ⑤ Patients with previous varus trichiasis, severe horn, conjunctiva infection and other eye diseases; Insufficient image quality, such as inconsistent field of view, poor image exposure, inaccurate image focus, stains, shadows or crescent shadows, etc.; There are systemic diseases; ⑧ Epilepsy, mental disorders unable to communicate normally; ⑨ Other circumstances judged by the investigator to be unsuitable to participate in the research

Ages Eligible for Study
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Minimum Age: 3 Years
Maximum Age: 12 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1% atropine<br>1% atropine eye drops, in the conjunctival sac, once a night, for 7 days | Drug: 1% atropine<br>* Daily application can be used for mydriasis and refraction examination Weekly long-term application can be used to control myopia<br>|
| Placebo Comparator: tropicamide<br>tropicamide eye drops, in the conjunctival sac, once every 5 minutes, after 3 consecutive doses, close eyes for 20 minutes | Drug: 1% atropine<br>* Daily application can be used for mydriasis and refraction examination Weekly long-term application can be used to control myopia<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| ciliary thickness parameters | ciliary thickness parameters, microns(um), photographed by ASOCT and measured by semiautomatic software | before intervention | 
| ciliary thickness parameters | ciliary thickness parameters, microns(um), photographed by ASOCT and measured by semiautomatic software | immediately after the last intervention | 
| the distance between ciliary muscle apex and scleral spur | ciliary muscle thickness, microns(um), photographed by ASOCT and measured by semiautomatic software | before intervention | 
| the distance between ciliary muscle apex and scleral spur | ciliary muscle thickness, microns(um), photographed by ASOCT and measured by semiautomatic software | immediately after the last intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| spherical equivalent | spherical equivalent(SE)，Diopter(D), measured by subjective optometry | before intervention | 
| spherical equivalent | spherical equivalent(SE)，Diopter(D), measured by subjective optometry | immediately after the last intervention | 
| axial length | axial length(AL), millimeter(mm), measured by IOL master | before intervention | 
| axial length | axial length(AL), millimeter(mm), measured by IOL master | immediately after the last intervention |