Combination Effect of Optical Defocus and Low Dose Atropine in Myopia Control

This study is a two-arm randomised controlled trial with a 18-month duration. Participants will be healthy Hong Kong Chinese schoolchildren with low to moderate myopia. The aim is to determine the combination effect of optical defocus and low dose atropine on myopia control in schoolchildren. Optical defocus will be delivered by Defocus Incorporated Multiple Segments (DIMS) spectacle lenses.

A total of 112 Hong Kong Chinese children aged 7 to 12 years (56 in each group) will be recruited and randomly allocated into two groups. One group will receive low dose atropine (0.01%) plus DIMS spectacles (ATD Group); another one will receive low dose atropine (0.01%) plus single vision spectacles (AT Group).

They must have no prior or current myopia control treatment, have no ocular or systemic diseases/abnormalities that affect visual function, refractive development or spectacle lens wear, and no previous intraocular or corneal surgery. They must not have allergy to atropine.

Their cycloplegic refraction and axial length will be monitored every six months for 18 months. The changes in refractive errors and axial length between groups will be compared.

Inclusion criteria

• Age at enrollment: 7 to 12 years
• Ethnicity: Hong Kong Chinese
• Myopia: -0.75D (in spherical equivalent) or above in both eyes
• Astigmatism: -1.50D or less in both eyes
• Anisometropia: 1.50D or less (in spherical equivalent) between two eyes
• Best corrected monocular visual acuity (VA): 0.04 logMAR or better
• Ocular health: No abnormalities in both internal and external ocular health
• Systemic health: No abnormalities such as cardiac and respiratory diseases
• Binocular vision: No strabismus, diplopia, suppression and other binocular abnormalities
• Normal colour vision
• No previous refractive surgery or use of myopic control interventions, such as atropine, orthokeratology, and specialized spectacle lenses and contact lenses for myopic control
• Able to wear the prescribed spectacles
• No known allergy to atropine

Exclusion criteria

• Eye disease or binocular vision problems (e.g., strabismus, amblyopia, oculomotor nerve palsies, corneal disease, etc.)
• Previous intraocular or corneal surgery
• Colour vision deficiencies
• Systemic disease that may affect vision, vision development (e.g. diabetes mellitus, hypertension, Down syndrome, etc.)
• Systemic disease that are contradictory to atropine (e.g. asthma, cardiac diseases, etc.)
• Previous gas permeable, soft bifocal, or orthokeratology contact lenses wear or bifocal / progressive addition lens spectacles wear or use of atropine or pirenzepine (longer than one month of usage)
• Previous or current participation in myopia control studies
• Allergy to cyclopentolate hydrochloride or atropine