Highly Aspherical Lenslet (HAL) and Binocular Vision (BV) Disorders [HALT X(T) Study]

Studies have been done to show that spectacles, atropine eye drops, and outdoor activities have some efficacy in slowing myopia progression in children, however most of such studies exclude children with significant eye conditions such as strabismus or nystagmus to isolate the effects of myopia control treatment. In this study, we would like to investigate whether these specialized glasses can effectively slow down the progression of myopia in children with strabismus. Since strabismus can affect visual development, this study would also be able to assess the effect and changes of eye misalignment (strabismus) with myopia control glasses. The study also aims to assess the efficacy of myopia control glasses on childhood myopia progression in children with strabismus due to the uncertainty clinicians face when prescribing myopia control glasses to these strabismic children.

Inclusion criteria

Age 5-12 years old Myopia of between -1D and -6D in at least 1 eye Progression of at least 0.5D within the last year Astigmatism less than 2.5D Exotropia Exophoria: horizontal deviation <40PD Esotropia (good control), Esophoria: horizontal deviation <40PD Any vertical strabismus: Vertical deviation <10 PD Intermittent exotropia (good, moderate, poor) Horizontal deviation ≥15 PD, vertical deviation ≤5 PD (?)

Exclusion criteria

VA poorer than logMAR 0.2 (6/9.5) in either eye Any other ocular condition (e.g. lens opacity, glaucoma) other than myopia, strabismus or nystagmus) Any medical/neurological condition which would interfere with subjects ability to co-operate with tests and attend follow-up appointments.

Plans of surgery for strabismus or nystagmus in the next year Constant XT). Past use of any other from of myopia control treatment (eg. atropine or myopia control glasses or contact lenses) within the last year.