Perceptual Learning Treatment for Amblyopia

Objectives. To develop a new treatment for amblyopia using a perceptual learning approach. Hypothesis to be tested. Our proposed experiments are designed to investigate whether practicing a grating detection task can improve vision in patients with amblyopia. Design and subjects. A total of 36 patients with amblyopia will be randomized allocated into two intervention groups: Group 1, perceptual learning therapy. Group 2, occlusion therapy. A control group comprising of 18 subjects with normal vision will be recruited for comparison. A battery of tests will be used to assess a range of visual functions before and after the treatment intervention. Study instruments. Grating acuity testing system Interventions. We have established a clinical protocol for acuity training. On each trial, a properly oriented stimulus will be presented randomly at one of the four locations on a flat monitor screen. The visual task is to indicate the location of the stimulus. Participants will be required to undertake 20 one-hour sessions of training. Main outcome measures. Resolution acuity, visual acuity, contrast sensitivity function

The intervention will be a vision therapy. On each trial, a properly oriented stimulus will be presented randomly at one of the four locations on a flat monitor screen. The visual task is to identify the location of the stimulus.

Grating acuity tests the participants' ability to resolve fine details. This study measures the change of grating acuity after 20 hours of vision training.

Visual acuity tests the participants' ability to resolve letters.This study measures the change of visual acuity after 20 hours of vision training.

Contrast sensitivity reflects the participants' sensitivity to identify low contrast visual stimuli. This study measures the change of contrast sensitivity after 20 hours of vision training.

Visual acuity tests the 3-D perception. This study measures the change of stereopsis after 20 hours of vision training.

Inclusion Criteria: Visual acuity in the amblyopic eye: 20/25 or worse Exclusion Criteria: Manifest eye disease & nystagmus

Levi DM, Li RW. Improving the performance of the amblyopic visual system. Philos Trans R Soc Lond B Biol Sci. 2009 Feb 12;364(1515):399-407. doi: 10.1098/rstb.2008.0203.

Li RW, Klein SA, Levi DM. Prolonged perceptual learning of positional acuity in adult amblyopia: perceptual template retuning dynamics. J Neurosci. 2008 Dec 24;28(52):14223-9. doi: 10.1523/JNEUROSCI.4271-08.2008.

Li RW, Ngo C, Nguyen J, Levi DM. Video-game play induces plasticity in the visual system of adults with amblyopia. PLoS Biol. 2011 Aug;9(8):e1001135. doi: 10.1371/journal.pbio.1001135. Epub 2011 Aug 30.