In vitro and in vivo experiments have shown that drug-resistant seizures can be optogenetically treated by activating halorhodopsin to inhibit excitatory neurons, or by activating channelrhodopsin-2 to stimulate inhibitory neurons. This strategy has been used to create a closed-loop system in which the onset of a seizure is detected by an EEG device, which prompts an optical fiber to activate the opsin and suppress seizure activity.

Although optogenetic therapy offers a high amount of precision, it is highly invasive. Furthermore, reliable methods to detect seizures are yet to be developed, attenuation limits how deep the light spreads, and tissue can become heated - altering behavior.