The Nature of Vergence Revealed by Electromyography

Abstract

This paper is one of a series of studies in vergence investigated by means of electromyography, parts of which have been previously reported.^1,2 The present study is concerned with accommodative and fusional vergence. The technique has been fully described in previous reports.^1-4 The energy levels of various positions have been determined with the integrator. I have deliberately inserted electrodes into only one muscle in many cases to minimize artefacts induced by multiple needle placements. The latter is a definitely limiting factor in evaluating fusional amplitudes and is conducive to blurriness of vision in the tested eye. Nevertheless, simultaneous studies of both medial and lateral rectus confirm the findings to be reported. The lateral rectus has often been selected for testing because the question of divergence is of considerable interest and because there is thus little interference with vision or examination. In some studies very fine electrodes (No. 31