Topical review: Ocular surface abnormalities in neurodegenerative disorders

SIGNIFICANCE In an aging population, the number of people living with neurodegenerative disease is projected to increase. It is vital to develop reliable, noninvasive biomarkers to detect disease onset and monitor progression, and there is a growing body of research into the ocular surface as a potential source of such biomarkers. BACKGROUND This article reviews the potential of in vivo corneal confocal microscopy and tear fluid analysis as tools for biomarker development. Corneal confocal microscopy, traditionally used for studying corneal health, offers high-resolution imaging of corneal nerves and has shown promise for examining systemic diseases such as Alzheimer disease and Parkinson's disease. Complementarily, tear fluid analysis, known for its ease of collection, reflects systemic changes in neurodegenerative conditions. CONCLUSION Together, these noninvasive techniques provide insights into disease onset and progression and hold potential for advancing diagnostic and treatment strategies.