1. A method for determining when the gaze of a subject is centered during visual field testing, wherein the subject has been instructed to fixate on a central location throughout the test, comprising: using one or more light sources to create one or more reflections from an ocular surface; displaying a series of test stimuli to the subject; imaging the subject's eye while each test stimulus is displayed; determining gaze descriptors for the eye for each test stimulus by analyzing the reflections of the light sources in the image; and determining inlier and outlier gaze descriptors using all or a subset of the gaze descriptors.