Clinical knowledge of the tear film molecular profile is lacking despite myriad research over the past 2 decades, according to a review published in Experimental Eye Research. A better understanding of tear analysis will improve clinicians’ ability to diagnose disease and enable better patient outcomes. 

A researcher illuminated this shortage in review articles discussing tear film biochemistry and sought to compile a review that summarized tear film components, discuss changes occurring during ocular and systemic disease, and identify challenges in detecting and quantifying tear compounds. The investigator used internet databases (Medline/PubMed, ScienceDirect, Google Scholar) published from January 2000 to October 2021 to obtain information on human tear compounds. 

The researcher identified numerous proteins, lipids, metabolites, and electrolytes present within the tear film and explained their varying  structures and functionalities. The investigator also asserts that sustainable production and expression levels of each of the tear compounds is essential to the health of the ocular surface. Tear biochemistry  alterations were noted for various environmental, ocular, and systemic conditions including dry eye disease, meibomian gland dysfunction, contact lens wear, stress, and cancer.   


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“Tear analysis might provide useful information for diagnosis and improved prognosis of treatment of diseases via early detection,” according to the researcher. “Therefore, similar to other body fluids, collection, storage and processing methods should be optimized and standardized to quantify the low concentrations of compounds in tears in order to implement tear analysis in routine healthcare delivery. Adaptation of a uniform and consistent techniques by researchers in the field, might also facilitate comparison of data among different research groups.”

The review may have been limited by failure to include pre-clinical trials.

Reference

Masoudi S. Biochemistry of human tear film: A review. Exp Eye Res. Published online May 1, 2022. doi:10.1016/j.exer.2022.109101