The action of the external muscles of the eye and the diagnosis of ocular paralysis : Professor, Elschnig's diagram / by Duncan Matheson Mackay, M.D.Edin., clinical assistant, Royal London Ophthalmic Hospital; refraction assistant, Royal Eye Hospital, Southwark; late house surgeon, Liverpool Eye and Ear Infirmary.

  • Mackay, Duncan Matheson
Date:
[1905?]
Catalogue details

Licence: In copyright

Credit: The action of the external muscles of the eye and the diagnosis of ocular paralysis : Professor, Elschnig's diagram / by Duncan Matheson Mackay, M.D.Edin., clinical assistant, Royal London Ophthalmic Hospital; refraction assistant, Royal Eye Hospital, Southwark; late house surgeon, Liverpool Eye and Ear Infirmary. Source: Wellcome Collection.

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    f 6 A glance at the diagram therefore at once reveals, in the case of paralysis of one rectus (superior or inferior), that the defect of movement of the eye is most distinctly seen,— or, in other words, that the difference in height between the two images (false and true) is the greatest,—if the eye under examination be elevated or depressed while in the position of abduction ; that is, for example, in the case of the right eye when it is turned to the right and upwards, or to the right and downwards. In the case of paralysis of one oblique the defect of movement is most distinctly seen,—or, in other words, the difference in height between the two images is the greatest,— if the eye under examination be elevated or depressed while in the position of adduction—that is, for example, in the case of the right eye when it is turned to the left and upwards or to the left and downwards. This may be translated into practice thus: if in any case of paralysis of an elevator or depressor the defect of movement of the eye (or the difference in height between the two images) is greater in the abducted position of the eye than in the adducted position one knows it is a rectus which is para¬ lysed. In the opposite condition, where the defect of move¬ ment (or the difference in height between the two images) is greater in the adducted position of the eye than in the abducted, one knows that it is an obliquus which is paralysed. A single example may still further elucidate the diagnosing of the paralysis from the examination of the double images by the use of this diagram. If the flame of the candle placed in the middle line reveals double images separated by distance in height, and if this distance in height increases the more the candle is lifted up one knows it is an elevator that is paralysed,—and an elevator of that eje, the image of which stands the higher (the image belonging to each eye is recognised, of course, by the aid of a coloured disc held before one of the eyes). Suppose, now, that this is the right eye. If, then, the elevated candle, always at the same height, be moved to the right and left, and if the distance in height between the two images increases as the candle is moved to the right (so that the eye tends to the abducted position) and diminishes as the candle is moved to the left (so that the eye tends to the adducted position), then we know that it is that elevator, the elevating action of which is the strongest in the abducted position, which is paralysed—that is, in this case the rectus superior of the right eye.