Objective:

To report evidence of a previously unrecognized posterior ocular lymphatic outflow (POLO) pathway and its implications for ocular fluid homeostasis.

Approach:

• Study Design: Researchers injected albumin-based MRI and near-infrared fluorescent tracers into the suprachoroidal space of adult mice and tracked their movement using various imaging techniques.
• Imaging Techniques: Techniques included magnetic resonance imaging, confocal scanning laser ophthalmoscopy, hyperspectral microscopy, and immunofluorescence.

Key Findings:

• Identification of a lymphatic route originating in the suprachoroidal space and draining into ipsilateral cervical lymph nodes.
• Tracer movement consistently followed a nasal route into the orbit before reaching submandibular lymph nodes within 20 minutes.
• Anatomical evidence for functional lymphatic vessels within the choroid, distinct from blood vessels.

Interpretation:

The findings suggest that lymphatic-mediated drainage may contribute to ocular fluid regulation throughout the eye, challenging the assumption that posterior fluid clearance relies primarily on passive transscleral movement.

Limitations:

• Tracer movement was captured at discrete time points rather than providing continuous flow measurements.
• The complete anatomical continuity of the POLO pathway has yet to be established.

Conclusion:

The study provides strong evidence for an active lymphatic component in posterior ocular drainage.

Sources:

• Translational Vision Science & Technology