Focus-out Glasses on Emmetropization in Chinese Children

Myopia is one of the most common eye diseases that cause visual impairment and blindness, and the high rate of myopia in young people is a major public health issue. Based on the clinical studies of optical defocusing to regulate eye growth and refractive changes through visual signal feedback, we hypothesize that early wearing of peripheral defocus glasses in children can slow down the process of emmetropization and even prevent the onset of myopia by producing more myopic defocusing. The aim of this study is to investigate whether wearing peripheral defocus glasses can effectively delay emmetropization in non-myopic children aged 6-8 years , and to further explore its effect on preventing the onset of myopia.

The study adopts a 2-year，single-centre, randomized, parallel-controlled trial with a non-blinded design. Subjects who pass the screening period will have their baseline data collected and will be assigned to the experimental or control groups according to the randomization principle. The experimental group will be fitted with Direct Emmetropia with Focus-out Glasses (hereafter referred to as DEFOG) to guide the emmetropization process. The control group will be given no treatment and will be a blank control. Baseline data including visual acuity, cycloplegic objective refraction, axis length, accommodation amplitude, strabismus examination, pupil size, choroidal thickness and peripheral retinal refraction will be measured when enrolled in the group and follow-up data will be measured at month 6, 12, 18 and 24. The primary interest of this study will be studied by comparing the difference in cycloplegic objective refraction changes between month 24 and baseline in the two groups of subjects.

Inclusion criteria

• Age: ≥6 and ≤8 years at enrollment.
• At least one parent' s Spherical equivalent refraction≤-3.00D.
• Spherical equivalent refractions (SERs) under cycloplegia: +0.50 to +1.50 diopters (D)
• Astigmatism ≤1.00 D .
• Anisometropia ≤1.00 D.
• Best Corrected Visual Acuity (BCVA) : 1.0 or better
• Provision of consent written by subject's legal guardian
• Willing and able to participate in all required activities of the study

Exclusion criteria

• Any of the following abnormalities on the ocular surface, such as trachoma, pemphigoid, chemical injury, heat burn, radiation injury, etc.
• Eyelid abnormalities (e.g. entropion, ectropion, tumor, edema, blepharospasm, incomplete eyelid closure, severe trichiasis, severe ptosis) ,which affect eyelid function in either eye
• Eye diseases such as strabismus, amblyopia, anisometropia, fundus diseases, and accommodation abnormality，etc.
• Prior treatment of myopia control in either eye, including but not limited to drugs, orthokeratology, low-level red-light therapy, etc.
• Noncompliance with measurement at enrollment.