Functional OCT with parfocal retinal stimulation enables multi-site optoretinography under a single dark adaptation

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Retinal Physiology

Background:

• Functional optical coherence tomography (OCT) allows depth-resolved imaging of stimulus-evoked intrinsic optical signal (IOS) changes in the retina.
• Objective optoretinography (ORG) using OCT is a noninvasive method for assessing retinal physiology.
• Traditional IOS imaging with raster-scan OCT is limited by lengthy acquisition times and the need for repeated dark-adaptation cycles.

Purpose of the Study:

• To develop an improved functional OCT system for rapid, objective optoretinography.
• To overcome the limitations of long acquisition times and multiple dark-adaptation cycles in IOS imaging.
• To establish a scalable framework for spatially and depth-resolved functional retinal mapping.

Main Methods:

• Developed a functional OCT system incorporating parfocal retinal stimulation.
• Co-registered visible-light stimulus and near-infrared OCT imaging beams on the retina.
• Utilized visible-light flashes with variable bleaching levels (1-100%) for stimulation.

Main Results:

• Achieved robust, spatially localized IOS confined to stimulated retinal regions.
• Observed a linear scaling of IOS amplitude with bleaching level up to ~20%, followed by saturation.
• Demonstrated that parfocal stimulation preserves dark adaptation in non-stimulated areas, enabling multi-site acquisition.

Conclusions:

• The parfocal stimulation strategy significantly enhances the efficiency of functional OCT imaging.
• This method provides an objective optical analogue to microperimetry for retinal assessment.
• Establishes a foundation for site-specific evaluation of photoreceptor physiology and retinal function.