1. A method for determining a visual performance metric of a test subject, the method comprising the steps of: estimating, by the processor, a model for at least one visual performance metric; identifying, by the processor, a stimulus pattern based, at least in part, on the estimated model, wherein the stimulus pattern comprises sinusoidally-modulated contrast gratings; generating, on a display, the stimulus pattern to present the stimulus pattern to the test subject; determining, by the processor, an Optokinetic Reflex (OKR) result indicating whether the stimulus pattern induced OKR in the test subject; updating, by the processor, the estimated model to incorporate the OKR result; and determining, by the processor, whether the updated model is acceptable.