Development of a versatile two-photon endoscope for biological imaging

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Microscopy

Background:

• Accurate imaging of the eye's aqueous outflow pathway is crucial for understanding and treating glaucoma.
• Existing imaging techniques may lack the resolution or in vivo capabilities required for detailed analysis.

Purpose of the Study:

• To develop and characterize a novel, catheter-type two-photon probe for high-resolution imaging of the eye's aqueous outflow pathway.
• To evaluate the probe's performance for both in vivo and ex vivo applications.

Main Methods:

• A catheter-type probe was constructed using a silica double cladding fiber, a spiral fiber scanner, and doublet achromatic lenses.
• The probe's components were integrated into a 2.8 mm diameter assembly within hypodermic tubing.
• Spatial resolution and fluorescence signal collection efficiency were optimized by evaluating different lens and fiber configurations.

Main Results:

• The probe achieved lateral and axial resolutions of 1.5 μm and 9.2 μm, respectively.
• Optimized configurations using doublet achromatic lenses and high numerical aperture double cladding fibers maximized signal collection efficiency.
• The probe successfully acquired images of human trabecular meshwork tissue, demonstrating its utility for live tissue imaging.

Conclusions:

• The developed miniature two-photon probe is a versatile tool for high-resolution imaging of ocular structures.
• Its design allows for in vivo and ex vivo investigation of the aqueous outflow pathway.
• This technology holds potential for advancing glaucoma research and diagnostics.