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Comment & Response
December 2018

Potential Sampling Bias in Investigation of Upright-Supine Test for Vertical Strabismus

Author Affiliations
  • 1Department of Ophthalmology, Duke Eye Center, Durham, North Carolina
  • 2Now with Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota
JAMA Ophthalmol. 2018;136(12):1427-1428. doi:10.1001/jamaophthalmol.2018.4172

To the Editor I want to congratulate Lemos et al1 on their excellent study and very important results that put into context the usefulness of the upright-supine test for vertifical strabismus in differentiating an acute or subacute skew deviation from a fourth nerve palsy (4NP). However, I do have a concern regarding one of the conclusions reached by the authors. The specific statement is the last part of the sentence that reads: “the absence of additional ocular motor and/or neurologic signs… may constitute a more useful clue.”1(p322) I appreciate that this statement is based on their finding that none of the 18 patients with 4NP in their study had additional neuroophthalmic or systemic neurological signs or symptoms, but I would argue that this conclusion may not be entirely correct because of a sampling bias and the neuroanatomy of 4NP.