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

"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.