Establishing New Treatment Approaches for Amblyopia: Perceptual Learning and Video Games

Amblyopia, a developmental abnormality that impairs spatial vision, is a major cause of vision loss, resulting in reduced visual acuity and reduced sensitivity to contrast. This study uses psychophysical measures to study neural plasticity in both adults and children with amblyopia.

Amblyopia, a developmental abnormality that impairs spatial vision, is a major cause of vision loss, resulting in reduced visual acuity and reduced sensitivity to contrast. Our previous findings (see Publications) show that the adult amblyopic brain is still plastic and malleable, suggesting that active approach is potential useful in treating amblyopia.The goal of this project is to assess the limits and mechanisms of neural plasticity in both normal and amblyopic spatial vision. This study uses psychophysical measures to study neural plasticity in both adults and children with amblyopia. Research participants will be asked to practice a visual discrimination task (perceptual learning) or to play video games with the amblyopic eye for a period of time. A range of visual functions will be monitored during the course of treatment.

perceptual learning, video games, visual plasticity, amblyopia treatment, pathophysiology of amblyopia, vision training, stereoacuity, strabismus

Participants will be required to play video games for a period of time: 1-2 hrs per session, 4-5 sessions/week for ~1-6 months

Participants will be required to practice a visual discrimination task (e.g. visual acuity, position acuity, contrast sensitivity, & stereoacuity) for a period of time: 1-2 hrs per session, 4-5 sessions/week for ~1-6 months

Participants will be required to cover the dominant eye during the day in order to push the brain to use the fellow amblyopic eye: 1-2 hrs per session, 4-5 sessions/week for ~1-6 months

"Visual acuity", the gold standard for vision testing, will be measured. Participants will be asked to read letters on a LogMAR letter chart. The smallest letters that can be read correspond to visual acuity (e.g., Snellen acuity of 20/20, letter-stroke width = 1 minute of arc).

"Stereoacuity" will be measured psychophysically using a new stereoacuity function test (1.25, 2.5, 5, 10, 15, & 20 cycles per degree) developed in our previous studies (Li et al 2016). A custom-built 4-mirror haploscope will be used to present a stereogram to each eye. Stereoacuity is the smallest stereo disparity that can be seen in binocular vision (in the unit of seconds of arc, arcsec). The conventional stereoacuity tests (including Randot Stereoacuity Test, Stereofly Test & Preschool Stereo Test) will also be used to measure stereoacuity. Participants will be asked to wear a pair of 3D glasses and to identify the target 3D pictures at various 3D levels. The smallest 3D disparities that can be seen correspond to stereoacuity (e.g. normal range of stereoacuity: 50 seconds of arc or better).

"Contrast sensitivity", the ability to detect low contrast / brightness, will be measured psychophysically for a range of spatial frequencies (1.25, 2.5, 5, 10, & 20 cycles per degree). Visual stimuli at different contrast levels will be displayed on a monitor screen. The smallest detectable stimulus contrast level will be measured in the unit of cd/m2.

"Positional acuity", the ability to detect a subtle positional offset between visual stimuli, will be measured psychophysically. Visual stimuli with different amount of positional offsets will be displayed on a monitor screen. The smallest detectable stimulus offset will be measured as position acuity, in the unit of seconds of arc.

Inclusion Criteria: adults and children with normal vision or amblyopia amblyopia: interocular VA difference of 0.1 logMAR or more Exclusion Criteria: any ocular pathological conditions, nystagmus

Li RW, Levi DM. Characterizing the mechanisms of improvement for position discrimination in adult amblyopia. J Vis. 2004 Jun 1;4(6):476-87. doi: 10.1167/4.6.7.

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, Provost A, Levi DM. Extended perceptual learning results in substantial recovery of positional acuity and visual acuity in juvenile amblyopia. Invest Ophthalmol Vis Sci. 2007 Nov;48(11):5046-51. doi: 10.1167/iovs.07-0324.

Li RW, Young KG, Hoenig P, Levi DM. Perceptual learning improves visual performance in juvenile amblyopia. Invest Ophthalmol Vis Sci. 2005 Sep;46(9):3161-8. doi: 10.1167/iovs.05-0286.

Li RW, Ngo CV, Levi DM. Relieving the attentional blink in the amblyopic brain with video games. Sci Rep. 2015 Feb 26;5:8483. doi: 10.1038/srep08483.

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.

Li RW, Tran KD, Bui JK, Antonucci MM, Ngo CV, Levi DM. Improving Adult Amblyopic Vision with Stereoscopic 3-Dimensional Video Games. Ophthalmology. 2018 Oct;125(10):1660-1662. doi: 10.1016/j.ophtha.2018.04.025. Epub 2018 May 18. No abstract available.

Li RW, Tran TT, Craven AP, Leung TW, Chat SW, Levi DM. Sharpening coarse-to-fine stereo vision by perceptual learning: asymmetric transfer across the spatial frequency spectrum. R Soc Open Sci. 2016 Jan 20;3(1):150523. doi: 10.1098/rsos.150523. eCollection 2016 Jan.

Li RW, So K, Wu TH, Craven AP, Tran TT, Gustafson KM, Levi DM. Monocular blur alters the tuning characteristics of stereopsis for spatial frequency and size. R Soc Open Sci. 2016 Sep 21;3(9):160273. doi: 10.1098/rsos.160273. eCollection 2016 Sep.

Li RW, Levi DM, Klein SA. Perceptual learning improves efficiency by re-tuning the decision 'template' for position discrimination. Nat Neurosci. 2004 Feb;7(2):178-83. doi: 10.1038/nn1183. Epub 2004 Jan 18.