Using light, optoretinography assesses the stimulus-evoked response of photoreceptors. Current systems employ adaptive optics (AO) to achieve cellular-level resolution and quick volume captures to monitor a single cone’s reaction with enough sampling across time. Because the systems are difficult to use, they are not suitable for use in clinical settings where ease of use and high throughput are desired. For a study, researchers sought to determine if a less complicated research-grade imaging system without AO could detect light-evoked changes in the retina when a stimulus was delivered.
For OCT, the imaging system employs a 100 kHz swept source, and a tracking laser scanning ophthalmoscope is connected with the sample arm for active eye-tracking. It served as a correction signal for the OCT, reducing spurious phase noise caused by eye movements. During OCT imaging, the stimulus was provided by a 555 nm LED (single flash and 10 Hz flicker). Clearly, without AO, the resolution was lower, and signals were a collective response from tens of photoreceptors, resulting in phase shift measurements between scattering speckle fields rather than well-defined single reflections from within a photoreceptor.
Improper eye tracking could also have a negative impact on the phase-sensitive imaging required to see ORG signals. On the other hand, the capacity to monitor any stimulus-evoked response with regular OCT would make optoretinography more accessible for studying human vision and novel functional biomarkers of retinal disorders.