Optical imaging to evaluate retinal activation by electrical currents using suprachoroidal-transretinal stimulation.

Area of Science:

• Ophthalmology
• Neuroscience
• Biomedical Optics

Background:

• Electrical stimulation of the retina is a potential therapeutic approach.
• Monitoring retinal neural activity non-invasively is crucial for understanding visual processing and disease.
• Optical imaging techniques offer promise for real-time assessment of retinal function.

Purpose of the Study:

• To evaluate a novel optical imaging fundus camera's ability to detect retinal reflectance changes following electrical suprachoroidal-transretinal stimulation (STS).
• To investigate the relationship between the magnitude of reflectance changes and the intensity of electrical stimulation.
• To correlate optical imaging findings with electrophysiological recordings of retinal activity.

Main Methods:

• Focal electrical STS was applied to ten cat eyes using a scleral electrode and a vitreous reference electrode.
• Near-infrared fundus images were captured every 20 milliseconds for 26 seconds, before, during, and after STS.
• Reflectance change maps were generated by image subtraction, and STS-evoked potentials (EPs) were recorded from the optic chiasma.

Main Results:

• Retinal reflectance changes were observed approximately 0.5 seconds post-STS, localized around the stimulation site.
• The intensity and area of reflectance changes were directly correlated with stimulus current intensity.
• A strong correlation (R² = 0.82) was found between the area of reflectance changes and the amplitude of EPs.

Conclusions:

• The newly developed optical imaging fundus camera successfully detected localized retinal reflectance changes induced by STS.
• These reflectance changes appear to reflect the activity of retinal neurons stimulated electrically.
• The findings suggest optical imaging can serve as a valuable tool for assessing retinal neural responses to electrical stimulation.