Response characteristics of objective perimetry in persons living with epilepsy

Purpose: To investigate safety and visual-field changes in people with epilepsy undergoing multifocal Pupillographic Objective Perimetry (mfPOP). Methods: 15 people with epilepsy and 15 controls underwent mfPOP in the context of routine clinical EEG testing. Safety measures comprised the proportion of participants developing an aura or seizure, a photoparoxysmal response, or increased epileptiform activity on their EEG during mfPOP. Pupil responses were obtained concurrently from 44 regions/field of each eye. Changes in standardised amplitude of constriction and time-to-peak were compared between people with generalised and focal epilepsy, and controls. Results: No participant developed an epileptic aura or clinical seizure during (or after) testing. One participant demonstrated EEG evidence of a focal subclinical seizure which began before mfPOP testing and continued unchanged during testing. Regional field sensitivities were increased in people with generalised epilepsy (+3.80 +/- 1.43 dB compared to controls) but were reduced in individuals taking antiepileptic medication (-4.04 +/- 1.74 dB). An extra delay of 24.9 +/- 10.2 ms was seen in the time-to-peak of the responses in people with focal epilepsy. Based on receiver-operating characteristic analyses, discrimination of people with epilepsy from controls was greatest when using the 4 to 10 most abnormal visual field regions of each eye (%AUC 77.3 +/- 9.70). Significance: In the absence of any safety signal, mfPOP appears harmless in people with epilepsy. The observed abnormalities in per-region sensitives and delays suggest that mfPOP may provide significant new insights into the study of epilepsy.