A review of the literature regarding abnormalities found in amblyopic eyes relative to the crowding phenomenon, pupil and contrast sensitivity function, EOG, ERG, PERG, VEP, OKN, and accommodation are discussed. Clinical observations, available tests, and basic science investigations continually force us to alter our definitions and the concepts that help us to better understand how to diagnose and treat patients with amblyopia. Accommodation has previously been shown to be impaired in some amblyopic eyes. A new recording test, i CAT (infrared consensual accommodation test), is described. This dynamic technique allows us to study accommodation simultaneously in the fixing and nonfixing eye. By plotting luminance profile curves, we can quantify accommodative amplitude and look at interocular differences.