Ocular Surface Disease In Neurodegenerative Disorders

The purpose of this review was to examine ocular surface disease (OSD) in neurodegenerative disorders (ND), focusing on tear film, tear biomarkers and corneal sensitivity in conditions such as Alzheimer’s, Parkinson’s, multiple sclerosis, and glaucoma. It also explores emerging therapeutic strategies for managing OSD in these patient populations.

University Hospital Center Zagreb, Zagreb, Croatia

A systematic search of available literature was conducted in electronic databases PubMed, Scopus, Web of Science, and the Cochrane Library, focusing on noninvasive ocular surface assessments in ND. The search utilized keywords such as “ocular surface disease,” “neurodegenerative disorders,” “tear film,” “tear biomarkers,” and “corneal sensitivity.” Only studies published in English were considered, and relevant findings were analyzed qualitatively.

ND are linked to reduced corneal sensitivity, altered tear osmolarity and impaired tear function. Elevated inflammatory markers such as IL-6, IL-8, TNF-α, and MMP-9, along with dicreased Brain-Derived Neurotrophic Factor (BDNF), are particularly notable in multiple sclerosis and glaucoma. Additionally, disease-specific tear biomarkers, amyloid-beta and tau proteins in Alzheimer’s, and altered alpha-synuclein in Parkinson’s, highlight their potential for noninvasive disease monitoring. Oxidative stress markers and distinct proteomic profiles further indicate ocular surface involvement in neurodegeneration. Tear substitutes, anti-inflammatory and neuroprotective agents show promise in improving ocular surface stability and patient comfort.

Ocular surface alterations, reduced corneal sensitivity, and tear film changes may serve as early indicators of neurodegeneration. Tear biomarkers offer a noninvasive approach for early diagnosis and disease monitoring. Further research is required to standardize assessment protocols and validate biomarkers for clinical application.