The following observations are based on the study of 200 cases examined for errors of refraction and lines of regard. Measurements were taken with the following objects in view: To determine the relation of the orbits to the plane of the face in the anomalies of refraction and the relation of the visual lines to the varying positions of the axes of the orbit, also to obtain suggestions for a possible anatomic cause or the varying so-called anomalies of the extra-ocular muscles and to explain the anomalies of the line of regard.
Taking the horizontal plane as measured through the attachment of the orbicularis-palpebrarum for the transverse direction (Fig. 1), and from the same points to the fossa on the superior maxilla toward the median line and over the root of the canine tooth for the vertical direction (d, d), we have for our purpose the base lines of the
COLBURN JE. THE ANATOMY OF THE OCULAR MUSCLES AND THEIR ACCESSORY STRUCTURES AND THE PHORIAS AND TROPIAS.. JAMA. 1902;XXXIX(16):964-968. doi:10.1001/jama.1902.52480420016001d