Letter to the Editor
I read with interest the article by Brodsky and Karlsson (1) and the authors' caution that tethering and buckling of the central lower eyelid in down gaze of patients with monocular elevation deficiency can simulate impaired infraduction in the involved eye. However, I wish to express a different opinion on the description of the figure shown by the authors.
Indeed, contrary to the description submitted, figure 1C does in fact demonstrate a deficit of infraduction of the abnormal right eye. Two clear landmarks can be used to come to that conclusion: first, the relative alignment of the upper limbus of each eye that clearly shows a lack of adequate depression movement of the affected eye. Second, the rounded pupil image of the right eye, as opposed to its oval-shaped counterpart (0.5 mm difference in vertical diameter), is in keeping with the difference in downward gaze position of the 2 eyes. Unfortunately, in this case, the pictures do not show which eye is fixating in down gaze due to the lack of corneal light reflection. Furthermore, there is no photographic documentation of ductions.
A review of some of the key publications on double elevator palsy shows a dramatic similarity with the documentation by Brodsky and Karlsson. For example, 4 of 5 cases with adequate pictorial documentation show a hyperdeviation in down gaze of the abnormal eye in textbooks by both Rosenbaum and Santiago (2) and von Noorden and Campos (3). Surprisingly, this deviation in down gaze is poorly discussed throughout the literature, most of the attention being directed at the classical findings of good alignment in primary position, a deficit of elevation in adduction and abduction, and the presence in some patients of a Bell phenomenon.
Finally, this deficit in depression of the abnormal eye referred to here and illustrated by the authors could be an indicator of a miswiring of either the superior rectus or the inferior rectus, another example of the ever-growing spectrum of congenital primary extraocular cranial neuropathies.
1. Brodsky MC, Karlsson V. Monocular elevation deficiency (“double elevator” palsy): a cautionary note. J Neuroophthalmol. 2011;31:56–57
2. Rosenbaum A, Santiago A Clinical strabismus management. 1999 Philadelphia, PA Saunders:273
3. von Noorden G, Campos E Binocular vision and ocular motility. 20026th edition St. Louis, MO Mosby:442–443