• Subject or legal authorized representative/guardian must be able to provide written informed consent signed prior to any study-specific procedures being conducted.

• Individuals aged 18-75 years at the time of consent.

• Subject has a diagnosis and history of a PPR with or without a diagnosis of epilepsy.

• Subjects receiving zero to three concomitant antiseizure medications (ASMs).

‣ Benzodiazepines: the chronic use of a benzodiazepine for any indication will be allowed and will be counted as an ASM.

⁃ Vagus nerve stimulator (VNS)/responsive neurostimulation (RNS): VNS/RNS will not be counted toward the number of concomitant ASMs. Subjects with surgically implanted VNS/RNS will be allowed to enter the study if all the following conditions are met:

• The device has been in place for 1 year or more prior to the screening visit.

∙ The settings have remained constant for 3 months or more prior to the screening visit and remain constant throughout the study.

∙ The battery is expected to last for the duration of the study.

• At least 3 of the EEGs performed during the screening visit must have an intermittent photic stimulation (IPS)-induced SPR of ≥3 points on a frequency assessment scale in the same eye condition, with documented confirmation by the Epilepsy Study Consortium, Inc. (ESCI).

• Subject is in otherwise good health (with the exception of epilepsy), as determined by the investigator and documented in the medical history.

• Subject has a body mass index (BMI) between 18 and 40 kg/m2.

• Subject agrees to refrain from strenuous exercise which is not within the subject's normal daily routine the day before screening, as determined by the investigator.

• Female subjects of childbearing potential and all men: agree to use of highly effective methods of contraception during the study and for 28 days after last dose of study drug.

⁃ Subject is able to communicate with the investigator and to understand and comply with all study requirements.