purpose: to evaluate the effect of vertical prism induced stress on binocular visual evoked potentials. methods: using checkerboard stimulus patterns in two spatial frequencies (sfs) of 0.48 cpd as a low sf and 2.18 cpd as a moderate sf reversing with temporal frequency of 4 hz, the effect of increasing visual stress using vertical prisms of 0, 1, 2 and 3 prism diopters on binocular visual evok...

PURPOSE Although significant amounts of vertical misalignment could have a noticeable effect on visual performance, there is no conclusive evidence about the effect of very small amount of vertical disparity on stereopsis and binocular vision. Hence, the aim of this study was to investigate the effects of induced vertical disparity on local and global stereopsis at near. MATERIALS AND METHODS...

Vertical fusional vergence (VFV) normally compensates for slight vertical heterophorias. We employed magnetic resonance imaging to clarify extraocular muscle contributions to VFV induced by monocular two-prism diopter (1.15°) base-up prism in 14 normal adults. Fusion during prism viewing requires monocular infraduction. Scans were repeated without prism, and with prism shifted contralaterally. ...

OBJECTIVES To test the previous findings of Enright that disparity-induced vertical vergence is mediated primarily by the oblique muscles, and to relate this normal eye movement pattern to the eye movement pattern seen in subjects with dissociated vertical deviation. METHODS Sixteen normal volunteers underwent 55 measurements of the cycloversion associated with prism-induced vertical vergence...

We examined the changes in Listing's plane resulting from prismatically induced vergence. The three-dimensional angular positions of the two eyes were compared in normal subjects wearing search coils and gazing at targets 1.9 m away with and without prisms. For horizontal base-out prisms each degree of convergence in one eye yielded 0.72 deg of temporal rotation of Listing's plane in that eye. ...

PURPOSE To find out whether adaptation to a vertical prism involves more than fusional vertical eye movements. METHODS Adaptation to a vertical base-up 3 prism diopter prism was measured in a custom-programmed Maddox test in nine visually normal emmetropic subjects (mean age 27.0 ± 2.8 years). Vertical eye movements were binocularly measured in six of the subjects with a custom-programmed bin...

Postural control in upright stance requires the central integration of visual, vestibular, somatosensory (as cutaneous receptors) and proprioceptive (as joint receptors) inputs. Clinical studies seem to indicate an association between vertical heterophoria (VH) and balance control. The purpose of the study was to simulate a VH and examine its influence on body stabilisation in quiet stance. We ...

A large perfect crystal interferometer with two interference loops offers novel applications in neutron interferometry. Coherent beam manipulation with special prism and phase shifter arrangements is discussed and prism materials that are able to preserve beam coherence in case of thicker prisms are investigated. A set of four identical prisms has been used to determine the vertical coherence f...

BACKGROUND Whether prism, especially base-up prism, affects the area of the retina used for fixation in a patient with central scotoma has been a controversial subject for 35 years. Our pilot study employed microperimetry to evaluate the effect of base-up prism on the fixation locus, or preferred retinal locus (PRL), in subjects with central scotoma. METHODS We used a microperimeter to assess...