Impact of Attrition, Intercellular Shear in Dry Eye Disease: When Cells are Challenged and Neurons are Triggered.

Gysbert-Botho Van Setten

doi:10.3390/ijms21124333

Abstract

The mechanical component in the pathophysiology of dry eye disease (DED) deserves attention as an important factor. The lubrication deficit induced impaired mechano-transduction of lid pressure to the ocular surfaces may lead to the dysregulation of homeostasis in the epithelium, with sensations of pain and secondary inflammation. Ocular pain is possibly the first sign of attrition and may occur in the absence of visible epithelial damage. Attrition is a process which involves the constant or repeated challenge of ocular surface tissues by mechanical shear forces; it is enhanced by the thinning of corneal epithelium in severe DED. As a highly dynamic process leading to pain and neurogenic inflammation, the identification of the impact of attrition and its potential pathogenic role could add a new perspective to the current more tear film-oriented models of ocular surface disease. Treatment of DED addressing lubrication deficiencies and inflammation should also consider the decrease of attrition in order to stimulate epithelial recovery and neural regeneration. The importance of hyaluronic acid, its molecular characteristics, the extracellular matrix and autoregulative mechanisms in this process is outlined. The identification of the attrition and recognition of its impact in dry eye pathophysiology could contribute to a better understanding of the disease and optimized treatment regimens.

Highlights

Attrition is defined as a decrease or reduction in numbers, size, or strength: a process of making something weaker by repeatedly attacking or exerting processes leading to weakening of resistance
Attrition has been used as a term for the description of a process involving the constant or repeated challenge of ocular surface tissues by mechanical forces in association with glaucoma surgery [1]
As a summarizing term of constant wear and challenge, the term attrition has been even used in psychology as one of the processes of challenges potentially leading to a burnout [5]

Summary

Introduction

Attrition is defined as a decrease or reduction in numbers, size, or strength: a process of making something weaker by repeatedly attacking or exerting processes leading to weakening of resistance. Pain and pain sensations precede visible tissue alteration and could offer an explanation for the mystery of the dissociation of signs and symptoms This dissociation is one of the key issues in the pathophysiology of dry eye and ocular surface disease. At preclinical stages, impaired function and composition of the extra cellular matrix (ECM) [7] (with fibronectin and hyaluronic acid (HA)) in areas with epithelial thinning could lead to the enhanced intercellular shear and stress Direct effects such as corneal epithelial erosions and mechanical tissue defects, as well as indirect effects such as cellular reactions, inflammation, and changes in tissue structure, can determine the extent and characteristics of ocular surface reaction and the occurrence of ocular pain, i.e., the intensity of dry eye disease (DED). The concept of attrition allows one to reevaluate the model of the vicious circle of DED [8] and its components

Characterizing Attrition

Epithelial Lesions—The Effect of Attrition

Reducing the Impact of Attrition

Conclusions