Corneal confocal microscopy: ready for prime time.

Area of Science:

• Ophthalmology
• Neuroscience
• Biomarker Discovery

Background:

• Corneal confocal microscopy (CCM) is an established ophthalmic imaging technique.
• CCM has emerged as a valuable tool for neurodegeneration research over the past two decades.
• The cornea possesses the body's densest network of sensory unmyelinated axons, making it ideal for studying nerve morphology.

Purpose of the Study:

• To review the utility of CCM as an imaging biomarker for neurodegeneration.
• To highlight CCM's reliability and reproducibility in quantifying corneal nerve morphology.
• To advocate for CCM's adoption as a Food and Drug Administration (FDA) endpoint in neurodegenerative disease clinical trials.

Main Methods:

• Corneal confocal microscopy (CCM) enables non-invasive, in vivo imaging of corneal nerve structures.
• Quantification of corneal nerve fiber length, density, and branching patterns.
• Analysis of existing literature and clinical trial data demonstrating CCM's role in neurodegeneration.

Main Results:

• CCM reliably quantifies corneal nerve morphology, reflecting peripheral and central neurodegenerative changes.
• Alterations in corneal nerve structure often precede or correlate with clinical symptoms of neurodegeneration.
• Early corneal nerve regeneration observed in intervention trials predicts functional improvements and neuroprotection.

Conclusions:

• Corneal confocal microscopy is a compelling, non-invasive imaging biomarker for neurodegeneration.
• CCM provides reproducible and cost-effective data relevant to neurodegenerative conditions.
• The evidence supports the inclusion of CCM as an FDA endpoint for clinical trials in neurodegenerative diseases.