Amblyopia
Conditions
Keywords
amblyopia, donepezil, perceptual learning, crowding, contrast sensitivity, visual acuity
Brief summary
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.
Detailed description
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.
Interventions
DRUGDonepezil
Donepezil will be administered to subjects three days before each training, and during training, to evaluate if donepezil improves the effectiveness of training.
BEHAVIORALSingle-letter training
Subjects will undergo training to identify single letters (10,000 trials, or 10 blocks per session for 10 sessions).
BEHAVIORALUncrowd training
Subjects will undergo training to identify letters closely flanked by other letters (10,000 trials, or 10 blocks per session for 10 sessions).
Sponsors
Dennis Levi
Study design
Allocation
RANDOMIZED
Intervention model
SEQUENTIAL
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Improvement in percent-correct performance in the respective training task | During training (performance will be summarized for each block of trials (a block takes approximately 5 - 10 min to complete). In other words, there should be 100 points of measurements throughout the training period.) | During training, for each trial, participants' responses can be categorized as correct or incorrect. The investigators will use the percent-correct performance to quantify the performance in each block, and this percent-correct performance will be measured throughout training (i.e. for each block on each day (10 blocks per day), and for 10 training days). |
| Visual acuity (the smallest letter the participants can see) | Immediately (one day) before and after training | The change in visual acuity before and after (one day before and one day after) training will be compared. The change will be expressed as a ratio. |
| Contrast sensitivity for identifying single letters (the lowest contrast required to identify letters) | Immediately (one day) before and after training | Contrast refers to the smallest difference in luminance between a letter and its background. This is a standard clinical measurement. Essentially, the lowest contrast letter is also the faintest letter that a participant can see. The change in contrast sensitivity for identifying single letters before and after (one day before and one day after) training will be compared. The change will be expressed as a ratio. |
| Crowding extent (the extent over which adjacent letters will affect the recognition of a letter) | Immediately (one day) before and after training | Crowding extent refers to the minimum distance between adjacent letters such that the presence of adjacent letters affects the recognition of a target letter. Usually the letter separation will be adjusted until the adjacent letters no longer affects how well the middle letter can be recognized. This distance is the crowding extent. The change in the crowding extent before and after (one day before and one day after) training will be measured. The change will be expressed as a ratio. |
Countries
United States
Outcome results
None listed