Two-photon imaging of the mouse eye.

Area of Science:

• Ophthalmology
• Microscopy
• Anatomy

Background:

• The conventional aqueous humor outflow pathway is crucial for maintaining intraocular pressure.
• Imaging this pathway in mouse models is essential for understanding glaucoma pathogenesis.
• Noninvasive techniques are needed to visualize these delicate structures.

Purpose of the Study:

• To image the conventional aqueous outflow pathway and adjacent structures in an intact enucleated mouse eye.
• To utilize noninvasive two-photon microscopy (2PM) for high-resolution imaging.
• To establish a baseline for future glaucoma studies in mouse models.

Main Methods:

• Two-photon microscopy (2PM), including two-photon autofluorescence (2PAF) and second harmonic generation (SHG), was employed.
• Fluorescein-conjugated dextran was used to perfuse blood vessels for anatomical reference.
• Eyes were processed for histological comparison with 2PM images.

Main Results:

• 3D 2PM imaging revealed a distinct region consistent with Schlemm's canal, connected to collector channels.
• These structures did not uptake the vascular tracer, indicating they contain aqueous humor, not blood.
• The trabecular meshwork (TM) showed collagen fibers via SHG signal.

Conclusions:

• 2PM is a promising noninvasive tool for imaging the conventional aqueous outflow pathway in mouse models.
• This methodology can aid in studying glaucoma mechanisms and testing therapeutic interventions.
• Further validation in live animals is underway.