Purpose: The purpose of this study was to determine whether experience improves detection of small eye movements similar to those seen in the cover test during ideal conditions.
Methods: Three groups of examiners with varying amounts of experience in eye movement detection tasks were studied. Eight examiners were 1st-year optometry students, six were 4th-year optometry students, and six were practicing optometrists. To determine thresholds for eye movement detection, examiners indicated the horizontal direction in which the eyes of one of the experimenters moved. The direction and extent of each eye movement was randomly selected. The extent of the eye movement was one of eight logarithmic steps from a maximum that was determined through an initial session where the approximate sensitivity of the examiners was found (generally +/- 1.75 prism diopters).
Results: Detection thresholds were determined by fitting the data with a cumulative Gaussian function. The mean horizontal eye movement eye movement necessary to obtain 99% correct judgments was 2.65 prism diopters for the 1st-year students, 2.47 prism diopters for the 4th-year students, and 2.40 prism diopters for the practicing optometrists.
Conclusions: The results indicate that during ideal conditions, little or no training is required for efficient detection of small eye movements.