The diagnosis of ocular paralyses / by Archibald S. Percival.

  • Percival, A. S. (Archibald Stanley), 1862-
Date:
[1897]
Catalogue details

Licence: Public Domain Mark

Credit: The diagnosis of ocular paralyses / by Archibald S. Percival. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    THE DIAGNOSIS OF OCULAR PARALYSES. By A. S. PERCIVAL, M.B., B.C. Cantab., Ophthalmic Surgeon to the Children's Hospital, Newcastle-upon-Tyne. The exact diagnosis of a paralysis of one or more of the ocular muscles is of extreme importance to both surgeon and physician; and while it seems at first sight to be surrounded with difficulties, it is hoped that many of these will disappear on a careful con- sideration of their nature. A brief reference to the anatomy of the orbital muscles must be first made. The four recti muscles arise from a common tendinous oval ring, which is attached to the inner side of the optic foramen, and then stretching obliquely across the sphenoidal fissure, is attached to its lower border. From this point the common origin again crosses the sphenoidal fissure—this time about its middle, and vertically—to join the upper edge of the optic foramen. The insertions of the recti tendons into the globe are too well known to need a description in detail. I would only call attention to the four intra-capsular ligaments, which are strong fibrous loops through which the recti pass to gain the interior of the capsule of Tenon. These intra-capsular ligaments, being attached through the capsule of Tenon to the bony walls of the orbit, act as pulleys, and protect the globe of the eye from pressure during contraction of the recti muscles. The external rectus abducts, the internal rectus adducts the eye; in fact, their action is one of simple rotation of the eyeball round a perpendicular axis through its centre of rotation. This centre of rotation is in emmetropic eyes about 13*5 mm. behind the apex of the cornea—that is, rather more than 1*7 mm. behind the centre of the visual axis. The line of action of the superior and inferior recti forms an angle of 27 degrees, with the sagittal (or antero-posterior) axis of the eyeball, consequently it is only when the eye is abducted 27 degrees that the action of the superior and the inferior recti is to