Study of Non-surgical Treatment Versus Observation in Asian Children With Intermittent Exotropia

Inclusion Criteria: 1. Age 3 to 12 years (inclusive) 2. IXT for distance or constant IXT for distance and either IXT or exophoria for near 3. IXT size of \> 10PD 4. Visual acuity in worse eye of at least 0.3 logMar (Snellen 6/12) 5. Visual acuity of no greater than 2 lines between eyes 6. Parents or guardian willing to accept randomization, and to continue with observation or treatment for at least 6-12 months, unless deterioration of strabismus or fall in best corrected visual acuity of worse than 0.3logMar (Snellen 6/12) in either eye 7. Investigator willing to observe IXT untreated for at least 1 year Exclusion Criteria: 1. Previous non-surgical treatment for IXT, or patch treatment for amblyopia within the last year 2. Prior strabismus, intraocular or refractive surgery or botulinium injection 3. Surgery planned within the next year 4. Prematurity (birth weight \< 1500g, gestational age \< 34 weeks), systemic illness (eg. cerebral palsy), syndrome (including craniosynostosis) or learning disability 5. Any ocular abnormality (cornea, lens or central retina); nystagmus or conditions that limit eye movements.