Dry Eye and Ocular Surface Disorders PDF

Preface

Dry eye is one of the most common ophthalmic medical problems. Complaints of dry eye are among the most common reasons patients seek help from eye doctors. Many patients with this condition have had to live with constant and occasionally debilitating pain. Research suggests that the impact on quality of life from this disease is approximately equal to that of angina.

Dry eye was traditionally considered to be an age-related dysfunction of the lacrimal gland. Based on this concept, therapy of dry eye was primarily directed toward lubricating and hydrating the ocular surface. This type of ocular surface palliation provided, at best, transient symptomatic relief due to the fact that this therapy does not address the underlying cause of the disease. Research over the last fifteen years has led to the acknowledgment that dry eye is a complex inflammatory syndrome of the tear-secreting apparatus that results in compositional changes of the tear film.

In 1993 a workshop convened at the National Eye Institute by Dr. Michael Lemp began the process of standardizing the nomenclature and diagnostic criteria involved in this problem. This was an important initial step in formalizing the subclassification of dry eye into aqueous deficient and evaporative loss.

We now understand that the tear film is secreted reflexively from the lacrimal functional unit, which is composed of the ocular surface tissues, the lacrimal glands, and their interconnecting sensory and autonomic innervation. This reflex secretion is initiated by subconscious stimulation of the highly innervated ocular surface epithelia. Almost all clinical "dry eye" conditions are due to dysfunction of this integrated functional unit. This may result in a decrease in the quantity of tears, but more importantly it leads to changes in tear composition that result in loss of tear film integrity and promote inflammation.

In this book, rather than following the traditional view of "dryness" as the putative cause of ocular surface disease, we have defined dry eye as an inflammatory disease of the lacrimal functional unit resulting in tear film compositional changes. We refer to this syndrome as LKC (lacrimal keratoconjunctivitis). This approach allows us to recognize the array of clinical conditions resulting in or from a dysfunctional tear film.

As evidence mounted in support of these concepts, we determined that there was a need to coalesce this body of research into a single usable reference.

The focus of this book is to make dry eye (LKC) a recognizable clinical entity based on the inflammatory paradigm.

Contributors to this book are internationally recognized investigators in individual aspects of lacrimal physiology and inflammation research. They were asked to use the lacrimal functional unit as the central theme when writing their chapters. Key illustrations in the book were prepared by Elaine Kurie, who did a masterful job capturing the concepts and new information.

We feel that the strength of this book is the comprehensive and unified approach to the understanding of this disease. We hope that you will use it as a guide to the pathophysiology, diagnosis, and treatment of LKC.