Abstract

According to one view, only stimuli presented to the fovea can elicit accommodative responses. However, clinicians report accommodation in patients with central-field loss, suggesting that peripheral vision can play a role. We used a laser optometer to measure accommodation to central and peripheral targets in subjects with normal vision. The targets consisted of featureless black disks superimposed on a uniform white field. Disk radii were 1 °, 7°, 15°, and 30°. Subjects fixated a laser-speckle pattern at the center of the disk. Eye-movement recording confirmed the stability of fixation. Since images of laser speckle patterns remain sharp independent of focus, the circular contour of the black disk on the white background provided the only stimulus to accommodation. For each disk, we measured monocular accommodation as a function of light vergence to estimate the amplitude of accommodation for contours at different retinal eccentricities. Accommodation was observed at all eccentricities, but declined outward from the fovea. Typical amplitudes of 4-5 D were obtained for the 1 ° disk and 1-2 D for the 30° disk. We conclude that peripheral vision is capable of eliciting accommodation. The possibility that peripheral accommodation is mediated by convergence accommodation is discussed.

© 1985 Optical Society of America