TFOS DEWS II - Introduction

The purpose of this report is to review our understanding of the pathophysiology of DED, highlighting those advances that have occurred since the TFOS DEWS report [1]. Our general thesis is that DED is initiated by desiccating stress and perpetuated by a Vicious Circle of ocular surface inflammation.
The raison d'etre of the eye is sight and the precorneal tear film and the cornea provide the first refractive element of the eye that focuses an image of the visual world upon the retina. To maintain optical quality, the tear film must be constantly replenished by blinking and tear secretion. Without this, the tear film would destabilise and the surface of the eye would be exposed to damaging desiccation. Various mechanisms are in place to achieve homeostasis.