Comprehensive, High-Spatiotemporal-Resolution Intravital Two-Photon Imaging of the Mouse Conventional Outflow...

Area of Science:

• Ophthalmology
• Microcirculation
• Fluid dynamics

Background:

• The conventional outflow pathway is crucial for regulating intraocular pressure.
• Understanding the fine structures and dynamics within this pathway is essential for glaucoma research.
• Current imaging techniques lack the spatiotemporal resolution to visualize these dynamics in vivo.

Purpose of the Study:

• To develop an advanced intravital imaging method for high-resolution visualization of the mouse conventional outflow pathway.
• To investigate the detailed structures and dynamic processes within the Schlemm's canal and collector channels.
• To explore the role of platelets and aqueous humor flow in this pathway.

Main Methods:

• Intravital two-photon imaging was performed in mice using fluorescent reporters (EGFP, Prox1-reporter, mito-Dendra2).
• The study visualized the perilimbal vein, collector channels, Schlemm's canal, and trabecular meshwork.
• Histological evaluation of Schlemm's canal was conducted in human glaucoma patients.

Main Results:

• High spatiotemporal resolution imaging revealed the intricate structures of the conventional outflow pathway, including features resembling giant vacuoles.
• Platelet flow into and out of Schlemm's canal via collector channels was observed.
• Fast aqueous humor flow converging towards collector channels was documented, with variations in velocity and patterns.

Conclusions:

• The developed intravital imaging method provides unprecedented insight into the mouse conventional outflow pathway.
• Platelets dynamically interact with Schlemm's canal, potentially influencing aqueous humor outflow.
• Collector channels appear to play a role in the heterogeneous dynamics of aqueous humor flow.