PURPOSE: It has been suggested that the pupillary light reaction is relatively preserved in the affected eyes of patients with Leber hereditary optic neuropathy (LHON). To test the hypothesis that visual-pupillomotor dissociation exists in LHON, we performed a retrospective study to evaluate the magnitude of the relative afferent pupillary defect (RAPD) in patients who had experienced monocular visual loss. We also compared the size of the measured RAPD with the size of the RAPD that would be expected on the basis of documented visual field loss. METHODS: We identified a cohort of patients with LHON and monocular visual loss, whose pupillary reactions had been quantified using neutral density filters. From a review of the case records, we determined whether an RAPD was present, as well as the magnitude of the documented RAPDs. We also calculated the expected size of the RAPD for each patient, using previously established templates that correlated the size of the RAPD with the degree of visual field loss. RESULTS: An RAPD was identified in all 10 patients in this study. There was no significant difference between the size of the measured and predicted RAPD, nor did the size of the RAPD correlate with visual acuity or the time interval between the onset of visual loss and evaluation. CONCLUSION: The results of this study do not support the hypothesis that visual-pupillomotor dissociation is a common feature of LHON.
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