A guide to the isolated dilated pupil
A. G. Lee, K. H. Taber, L. A. Hayman and R. A. Tang
Department of Ophthalmology, Baylor College of Medicine, Houston, Tex, USA.
The poorly reactive and dilated pupil observed in a comatose patient is
often thought to represent an acute third nerve palsy owing to brain
herniation or aneurysm. In the well patient, however, the isolated dilated
pupil is unlikely to be owing to a third nerve palsy. It is more commonly
owing to other benign causes such as local iris sphincter abnormalities,
pharmacologic dilation, tonic pupil syndrome, or sympathetic irritation.
This article presents a diagnostic flowchart to help the primary care
physician analyze this problem and prevent costly and unnecessary imaging
of these patients.
