Ocular Motility Evaluation of Strabismus and Myasthénie Gravie by M. Edward Wilson, Jr, MD
American Academy of Ophthalmology, PO Box 7424, San Francisco, CA 94120-7424. Telephone: 415-561-8540; FAX: 415-561-8575. Continuing Ophthalmic Video Education #0250943, 1993. Duration: 25 minutes. $85.
M. Edward Wilson, Jr, MD, and the American Academy of Ophthalmology have given us a special gift in this videotape. Although said to be intended for the ophthalmic assistant, nurse, or resident early in their training, this tape is sufficiently comprehensive hi covering the strabismus examination that residents should be encouraged to review it again in the second and third years of their training. The tape begins with a brief review of very basic EOM anatomy and physiology, including a refreshingly updated pictorial depiction of the position of the EOM in relation to the globe in various positions of gaze. Only the distal portions of the vertical recti, for example, are shown moving from side to side as the eye moves from abduction into adduction. The physiologic rationale of testing in the cardinal positions is reviewed. Versions are demonstrated in a way that encourages the student to think of which pairs of yolk muscles are acting maximally in each of the cardinal positions of gaze.
Each of us has our favorite way of teaching the cover tests; I like to use the concepts of qualitative versus quantitative in a traditional fashion. Wilson follows the terminology and sequence of tests as described in the Academy Basic and Clinical Science Course since 1983. He describes the first of three cover tests, the monocular cover-uncover test, as a way to detect and distinguish between phorias and tropias. He initially introduces quantitation with prisms in association with the second test, the alternate cover test, to measure the total deviation. He de-emphasizes the simultaneous prism cover test, the third test, saying that it is useful mainly in characterizing the patient with small esotropías and larger esophorias. Perhaps this is why I frequently see residents recommending surgery inappropriately when the esotropia is small and the esophoria is much larger.
The measurement of the deviation in the oblique cardinal positions for patients with superior oblique palsies is demonstrated by repositioning the patient's head so that the patient is looking down and to the left, etc, but still at the same square of letters at the other end of the eye lane. I find this technique difficult to perform without simultaneously tilting the head passively. I prefer house address numbers as fixation targets attached to the walls of the eye lane in the oblique cardinal positions. As the patient looks at each number, I can be certain that there is no head tilting.
In spite of these concerns, I definitely recommend this tape because so many important details in the strabismus examination and the Tensilon test are reviewed rapidly with flawless demonstrations typical of the high quality we have come to expect from Academy teaching tapes.