Increasing Patching for Amblyopia in Children 3 to < 8 Years Old

Amblyopia is the most common cause of monocular visual impairment in both children and young
and middle-aged adults. Both patching and atropine are accepted treatment modalities for the
management of moderate amblyopia in children.1 Many practitioners prescribe 2 hours daily
patching as initial therapy for amblyopia. However, many children fail to achieve normal
visual acuity in the amblyopic eye with this regimen. In a randomized trial conducted by
PEDIG comparing patching regimens, 71 of 92 patients with moderate amblyopia (77%) had
amblyopic eye visual acuity of 20/32 or worse after 4 months of patching 2 hours daily.2 In
another PEDIG randomized trial comparing patching to spectacles alone after a period of
refractive adaptation, patients were treated with 2 hours daily patching and followed every
5 weeks until there was no improvement in amblyopic eye acuity. Fifty-five of 70 patients
with moderate amblyopia (79%) and 14 of 14 patients with severe amblyopia (100%) had
best-measured amblyopic eye visual acuity of 20/32 or worse after a median treatment period
of 10 weeks.3 When improvement with initial therapy stops and amblyopia is still present,
treatment options include increasing the dosage of current treatment, switching to another
treatment, maintaining the same treatment and dosage for additional months, or combining
treatments. Many clinicians will choose to increase the dosage of the current treatment, in
part because families have become comfortable with that particular mode of treatment.
However, it is unknown whether increasing occlusion dosage will improve amblyopic eye visual
acuity in these patients. We are unaware of any reports of response to intensified treatment
of amblyopia.

Inclusion Criteria:

Major Eligibility Criteria for Run-in Phase

- Age 3 to < 8 years

- Amblyopia associated with strabismus, anisometropia, or both

- Visual acuity in the amblyopic eye between 20/50 and 20/400 inclusive

- Visual acuity in the sound eye 20/32 or better and inter-eye acuity difference >3
logMAR lines

- Amblyopia treatment within the past 6 months subject to the following stipulations:

- No more than 6 weeks of any amblyopia treatment other than spectacles (except
for patients being treated with 2 hours of patching per day who are entering the
study on treatment)

- No simultaneous treatment with patching and atropine

- No use of atropine in combination with the sound eye spectacle lens reduced by
more than 1.50 D

- Maximum level of treatment within the past 6 months:

- Patching: up to 2 hours daily

- Atropine: up to once daily

- Wearing spectacles with optimal correction (if applicable); if amblyopic eye acuity
is 20/80 or better, then VA must be stable in glasses. If amblyopic eye acuity is
20/100 or worse, then spectacles and patching can be initiated simultaneously.

Eligibility Criteria for Randomization:

- Amblyopic eye acuity of 20/40 to 20/160 with an inter-ocular difference of >2 lines,
or amblyopic eye acuity of 20/32 with 3 lines of IOD.

- Reasonable compliance with prescribed treatment, defined as wearing the patch at
least 10 hours per week.

Exclusion Criteria:

- Currently using vision therapy or orthoptics

- Ocular cause for reduced visual acuity (nystagmus per se does not exclude the patient
if the above visual acuity criteria are met)

- Prior intraocular or refractive surgery

- Known skin reaction to patch or bandage adhesives