Combining Donepezil With Perceptual Learning in Normal and Amblyopic Human The Effect of Donepezil on Perceptual Learning in Adult Amblyopia

The research deals with amblyopia or lazy eye, a condition that affects about 3% of the
population, and results in a variety of visual deficits. Recent work suggests that there is
limited neural plasticity in the visual system of adults with amblyopia. This study is aimed
at understanding and increasing this plasticity. In this study, the investigators aim to
understand how the amblyopic brain learns and how this process is affected by a drug called
donepezil, which is sometimes given as a treatment for Alzheimer's disease. The investigators
hope that this study will help to identify the chemical components that help the brain to
learn, as well as the mechanism of amblyopia. The investigators also plan to test the normal
periphery, as control.

In this study, donepezil will be administered while amblyopic subjects (or normally sighted
subjects tested in the periphery) are trained on a low-contrast single-letter recognition
task, or an uncrowd task (recognizing a letter closely embedded within two other letters).
Subjects will be asked to identify the target letter (the low-contrast single letter, or the
letter embedded within other letters). Training will take place for 10 consecutive days. Pre-
and post-tests will be conducted immediately before and after training, and will consist of
the measurements of visual acuity, crowding extent and contrast threshold for recognizing
single letters.

Subjects with amblyopia

Inclusion Criteria:

- corrected visual acuity being 20/30 or worse in the poorer eye (at least 20/20 in the
better eye)

- reduced stereoacuity

- normal retina

Exclusion Criteria:

- with other diagnosed eye diseases

Subjects with normal vision

Inclusion Criteria:

- corrected visual acuity at least 20/20 in each eye

- normal stereoacuity

- normal retina

Exclusion Criteria:

- with other diagnosed eye diseases