To determine the effectiveness of alternate occlusion therapy for the treatment of IXT among
patients aged 3 to < 11 years old.
Intermittent exotropia (IXT) is the most common form of childhood-onset exotropia with an
incidence of 32.1 per 100,000 in children. Before surgery, many cases of IXT are treated
using non-surgical interventions, such as part-time alternate occlusion. However, the
"alternating" occlusion with traditional patches is usually out of control. The investigators
are uncertain about the amount of "alternating" in patching treatment.
Here, the investigators introduce controlled intermittent alternating occlusion (CIAO)
therapy, which is provided by a new electronic device, -liquid crystal glasses. This study is
to determine the effectiveness of alternate occlusion therapy for the treatment of IXT among
patients aged 3 to < 11 years old. Children with IXT will be randomized into either an
observation group or a CIAO therapy group.
- Intermittent exotropia (manifest deviation) meeting all of the following criteria:
- Intermittent exotropia at distance OR constant exotropia at distance and either
intermittent exotropia or exophoria at near
- Exodeviation at least 15PD at distance OR near measured by prism and alternate
cover test (PACT)
- Exodeviation at least 10PD at distance measured by PACT
- No previous surgical or non-surgical treatment for IXT (other than refractive
- Visual acuity in the worse eye 0.3 logMAR or better (20/40 on ATS HOTV or 70 letters
on E-ETDRS) for children ≥ 3 years of age
- No interocular difference of visual acuity more than 0.2 logMAR (2 lines on ATS HOTV
or 10 letters on E-ETDRS) for children ≥ 7 years of age
- Investigator not planning to initiate amblyopia treatment
- No hyperopia greater than +3.50 D spherical equivalent in either eye
- No myopia greater than -6.00 D spherical equivalent in either eye
- No prior strabismus, intraocular, or refractive surgery
- No abnormality of the cornea, lens, or central retina
- Investigator willing to observe the IXT untreated for 3 years unless specific criteria
for deterioration are met.