3. Polarized and lens color effects on photoparoxysmal response

Introduction Approximately 5% of epilepsy patients’ photosensitivity can be detected on EEG recordings. This photoparoxysmal response (PPR) may prevent patients from performing their daily activities and also can result in seizures and anxiety. The objective of this study is to optimize the use of Z1 and other polarized and colored lenses for reducing PPR in epileptics. Purpose We propose that by covering central and temporal visual fields with either Z1 lenses plus side guards or elongated polarized lenses may suppress the PPR by altering the luminance and/or wavelength. Methods 22 pediatric patients with Type 4 PPR (Waltz et al.) were tested with and without Z1 lenses using photic stimulation from 1 to 21 Hz. 19 patients had primary generalized epilepsy (5 JME & 14 Absence), 2 had reflex epilepsy and 2 had Dravet’s Syndrome. Results Responses were classified into 3 groups: PPR disappearance, persistence or attenuation. 14 patients had reduced PPR (64%) and in 5 patients PPR disappeared (23%). 3 patients (13%) demonstrated persistence of the PPR with Z1 lenses. Several patients tested with side guards plus cobalt blue tint polarized lens sunglasses showed marked PPR reduction. Several patients tested with elongated polarized sunglasses covering the temporal visual field showed PPR attenuation. Placing a red lens over the photic stimulation lamp augmented the PPR from 1 to 19 Hz stimulation in several patients. A blue lens over the photic lamp resulted in attenuation or disappearance of the PPR at several photic stimulation frequencies in several patients. Conclusions Z1 and other blue lenses reduced the PPR in nearly all patients. Possible mechanisms include polarization, reduction of luminance, and filtering of red light. Further testing of photosensitive patients will be performed. Comparisons will be made between Z1, elongated polarized, cobalt blue, red and green Coppola, 2006 , Jeavons and Harding, 1975 , Newmark and Penry, 1979 , Binnie and Jeavons, 1992 , Quirk et al., 1995 , Kasteleijn-Nolst Trenit’e et al., 2002 , Takahashi and Tsukahara, 1976 .