Binocular iPad Sub-Study

Although patching treatment results in improved visual acuity for most amblyopic children,
some fail to achieve normal visual acuity after months or years of treatment. Even among
children who do achieve normal visual acuity with amblyopia treatment, the risk for
recurrence of amblyopia is high. Patching treatment is based on the premise that amblyopia is
a monocular disorder that can be treated by forcing use of the amblyopic eye. However, recent
studies have elucidated a clear link between binocular dysfunction and the complex
constellation of deficits that characterizes amblyopia, including visual acuity, vernier
acuity, fixation instability, fusional suppression, and risk for residual and recurrent
amblyopia. The association of binocular dysfunction and the myriad of monocular and binocular
deficits in amblyopia has led us to hypothesize that amblyopia is a monocular consequence of
a primary binocular obstacle to normal visual development.

Although binocular interaction does not normally occur in amblyopia, weak, noisy signals from
the amblyopic eye can contribute to binocular vision if suppression by the fellow eye is
reduced by signal attenuation, such as reduced stimulus contrast. In small cohorts of
amblyopic adults and schoolchildren, repeated practice with a binocular Falling Blocks iPod
game with reduced fellow eye contrast yielded modest visual acuity improvement after just 1-5
weeks (Hess et al 2010, 2012, 2014; Knox et al 2011; Li et al 2012). Recently, we showed that
the same binocular game app approach(reduced fellow eye contrast) could be adapted for home
use by amblyopic children on a larger iPad display (Li et al 2014; Birch et al 2014). These
games also were effective in improving visual acuity, and the visual acuity gains were
maintained for at least 6 months (Li et al 2014a, 2014b). The major limitation of both sets
of studies was that the games were not very interesting and quickly became tedious to play
day after day. To overcome this limitation, we propose to evaluate a new, more engaging
binocular iPad adventure game to determine whether practice with a binocular iPad games app,
with reduced fellow eye contrast, can improve visual acuity and reduce interocular
suppression in children with amblyopia.One group of participants will include 56 children
with anisometropic, strabismic, or combined mechanism amblyopia, age 4-10 years. The
participants will be randomly assigned to patch 2 hours daily patching (standard-of-care
treatment) or to play the iPad game app 1 hour per day 5 days per week for 2 weeks. Half of
the children will have had no prior treatment for amblyopia and the other half will have had
prior amblyopia treatment; these two subgroups will be randomized separately. A blocked
randomization order will be provided in sealed envelopes by our consultant statistician. A
second group of participants will include 40 children with deprivation amblyopia due to
cataract. The participants will be randomly assigned to continue their patching regimen (if
any) or to continue their current patching regimen and also play the iPad game app 1 hour per
day 5 days per week for 4 weeks. iPads with the game app are loaned to the family for the
duration of the study, Vision will be tested at baseline and at 2 weeks for the primary
outcome of change in visual acuity (for strabismic, anisometropic, and combined mechanism
amblyopia) or at baseline and 4 weeks (for deprivation amblyopia). At the primary outcome
visit, the patching group will be crossed over to play the iPad game app 1 hour per day 5
days per week and return for a secondary outcome at 4 weeks (for strabismic, anisometropic,
and combined mechanism amblyopia) or 8 weeks (for deprivation amblyopia). Families will have
the option to discontinue or to continue with the game app for up to 8 weeks, with testing
every 4 weeks.

Inclusion Criteria:

Age 4-14 years Female and male Amblyopia with amblyopic eye visual acuity 20/40-20/125,
fellow eye visual acuity 20/16-20/25, and interocular difference in visual acuity of 3
lines or more.

Anisometropic (with or without microtropia) or fully accommodative esotropia (no tropia
present with glasses), or deprivation amblyopia Wearing glasses (if needed) for 8 weeks or
no change in visual acuity with glasses wear for 4-6 weeks.

Must be able to demonstrate understanding and ability to play the Dig Rush game app during
the enrollment visit.

Signed informed consent obtained

Exclusion Criteria:

Prematurity ≥8 weeks Coexisting ocular or systemic disease Developmental delay Poor ocular
alignment (strabismus >5 prism diopters)