Chapter 139 Diseases of the Lacrimal System
The overall function of tears is to protect and nourish cornea, sweep debris into nasolacrimal canaliculi, and lubricate the eyelids. They also have a refractive function. An understanding of the anatomy and innervation of the lacrimal system, as well as the formation, composition, and function of the precorneal tear film, is important to the understanding of the physiology, pathogenesis, diagnosis, and treatment of its diseases.
ANATOMY AND PHYSIOLOGY OF THE LACRIMAL SYSTEM
Precorneal Tear Film
Innervation of the Lacrimal System
DISEASES OF THE LACRIMAL SYSTEM
Diseases of the lacrimal system can be divided into those that cause a decrease in any component of the preocular tear film or those that cause epiphora. Keratoconjunctivitis sicca is primarily caused by an immunemediated disease against the lacrimal glands, resulting in a decrease in the aqueous component of the precorneal tear film. The other, less common causes will also be discussed. Diseases that cause epiphora, or excessive tearing, are usually secondary to a problem with tear drainage or irritation from periocular hairs contacting the corneal surface. These and their appropriate therapies will also be discussed.
Keratoconjunctivitis Sicca
Keratoconjunctivitis Sicca Due to Quantitative Tear Deficiencies
Clinical Signs

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