Quantifying optic nerve axons in a cat glaucoma model by a semi-automated targeted counting method.

Area of Science:

• Ophthalmology
• Neuroscience
• Veterinary Medicine

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Accurate quantification of optic nerve axons is crucial for understanding glaucoma progression.
• Current methods for axon counting can be time-consuming and labor-intensive.

Purpose of the Study:

• To describe and validate a novel semi-automated targeted sampling (SATS) method.
• To assess the accuracy and reliability of SATS for optic nerve axon quantification.
• To compare the efficiency of SATS with traditional methods in a feline glaucoma model.

Main Methods:

• Optic nerve cross-sections from 15 cats (9 glaucoma, 6 normal) were processed for light microscopy.
• A semi-automated axon counting tool (SCT) was validated against manual axon counts (MAC).
• SATS and semi-automated full count (SAFC) methods were performed, with inter-rater agreement assessed using the intraclass correlation coefficient (ICC).

Main Results:

• Strong correlation between SCT and MAC (r = 0.9985).
• High correlation between SATS and SAFC (r = 0.9891) and excellent inter-rater agreement (ICC = 0.986).
• SATS required only 27% of the time for SAFC, demonstrating significant time efficiency.

Conclusions:

• The SATS method is a practical and rapid tool for estimating optic nerve axon counts.
• SATS provides a reliable means for quantifying axons in feline glaucoma models.
• This method can aid in glaucoma research and clinical assessments.