Robotic Visible-Light Optical Coherence Tomography Visualizes Segmental Schlemm's Canal Anatomy and Segmental...

Area of Science:

• Ophthalmology
• Anatomy
• Medical Imaging

Background:

• Schlemm's canal (SC) is crucial for aqueous humor outflow (AHO).
• Understanding SC anatomy and its response to drugs is vital for glaucoma treatment.
• Previous imaging methods have limitations in visualizing SC's segmental nature.

Purpose of the Study:

• To utilize robotic visible-light optical coherence tomography (vis-OCT) for studying the circumferential, segmental anatomy of Schlemm's canal (SC) in mice.
• To investigate the response of the aqueous humor outflow (AHO) pathway to topical pilocarpine administration using vis-OCT.

Main Methods:

• Anterior segment imaging was performed using a robotic vis-OCT system to maintain consistent illumination of the SC.
• Sixteen mice were imaged before and after topical administration of 1% pilocarpine or control artificial tears.
• Circumferential measurements of SC area and volume were analyzed.

Main Results:

• Circumferential vis-OCT provided high-resolution, in vivo imaging of the AHO pathways.
• Significant segmental variations in SC cross-sectional area were observed, with the largest area temporally and smallest nasally.
• Pilocarpine administration led to a significant increase in SC volume (26.8%) compared to controls (8.9%), with a greater effect observed superiorly and nasally.

Conclusions:

• Circumferential vis-OCT enables noninvasive, in vivo visualization of segmental SC anatomy and AHO pathways.
• The study confirmed the segmental nature of SC anatomy and its response to a muscarinic agonist (pilocarpine).
• Observed segmental drug responses in SC may have implications for patient responses to glaucoma medications.