Objective To demonstrate a unique abnormality of the pupillary light reflex in patients with autoimmune autonomic ganglionopathy (AAG).
Design Case series.
Setting Autonomic clinics at 2 university hospitals (University of Texas Southwestern Medical Center and Beth Israel Deaconess Medical Center).
Participants Seven patients with antibody-positive AAG.
Interventions All patients with AAG underwent either monocular or binocular infrared pupillometry using a standard 2-second light stimulus at a defined intensity. Findings were compared with those from healthy control subjects and patients with other autonomic disorders. The light stimulus used in this study was selected to eliminate the normal phenomenon of pupil escape.
Main Outcome Measures The time to onset of redilation as well as other indices of pupillary constriction to light stimulus.
Results Patients with AAG exhibited premature pupillary redilation (mean [SD], 1.02 [0.20] seconds) compared with healthy control subjects (mean [SD], 2.24 [0.10] seconds) and other patients with autonomic disorders (mean [SD], 2.30 [0.12] seconds) (P < .001). In healthy control subjects and patients with other autonomic disorders, pupillary redilation always followed the termination of the light stimulus; in patients with AAG, redilation consistently occurred during the light stimulus. In 1 patient, serial repetitive light stimulation further decreased the time to onset of redilation.
Conclusions Premature redilation of the pupil is a unique physiological feature seen only in patients with AAG. This phenomenon appears to be a manifestation of pupillary fatigue, a clinical correlate of defective synaptic transmission at the level of autonomic ganglia in antibody-positive AAG.