Imaging retinal capillaries using ultrahigh-resolution optical coherence tomography and adaptive optics

Area of Science:

• Ophthalmology
• Medical Imaging
• Biomedical Engineering

Background:

• Retinal microvasculature imaging is crucial for diagnosing conditions like diabetic retinopathy.
• Ultrahigh-resolution optical coherence tomography (UHR-OCT) combined with adaptive optics (AO) offers micrometer-scale 3D imaging capabilities.
• This advanced imaging technique (UHR-AO-OCT) holds promise for visualizing the fine details of retinal capillaries.

Purpose of the Study:

• To evaluate the potential of UHR-AO-OCT for detecting individual capillaries in the human retina.
• To assess the ability of UHR-AO-OCT to visualize the foveal avascular zone (FAZ) and its surrounding capillaries.
• To compare UHR-AO-OCT findings with established methods like entoptic diagrams and histology.

Main Methods:

• Acquired UHR-AO-OCT volumes centered on the fovea in seven healthy subjects.
• Compared UHR-AO-OCT images with entoptic diagrams, focusing on FAZ presence, capillary patterns, and FAZ size.
• Measured capillary diameter and depth range relative to retinal eccentricity.

Main Results:

• UHR-AO-OCT results strongly correlated with entoptic observations (R² = 0.86) for FAZ measurements.
• Average capillary diameter near the FAZ rim was approximately 5.1 micrometers, consistent with histological data.
• Capillary depth range increased with eccentricity, showing greater variability in subjects without a FAZ.

Conclusions:

• UHR-AO-OCT successfully visualizes numerous capillaries near the FAZ, including those of average size.
• The findings suggest that UHR-AO-OCT is capable of detecting the vast majority of retinal capillaries.
• This technology supports the potential for early detection of microvascular changes in retinal diseases.