tear film

pre·cor·ne·al film

a protective film, 7-9 nm thick, consisting of external oily, intermediate watery, and deep mucoprotein layers.
Synonym(s): tear film

tear film

A liquid consisting of lipids, water, and mucin that coats the outer surface of the eye, lubricating it.

Patient care

A reduction in the tear film causes a sensation of a dry or gritty eye, such as is seen in Sjögren's syndrome, keratoconjunctivitis, sicca, disorders of the lacrimal gland, and other conditions. Keeping eyelids clean, using artificial tears, and withholding medications that may reduce the tear film can prove helpful for some patients. Other treatments may include the wearing of moisture chambers around the eye, and eye lid surgery. Topical lubricants can be used for symptomatic relief.

film, precorneal

The field covering the anterior surface of the cornea which consists of lacrimal fluid and of the secretion of the meibomian and conjunctival glands. Its total thickness was thought to be about 9 μm but recent investigations have questioned that value and point to a much larger figure. It is composed of three layers: (1) The deepest and densest is the mucin layer (or mucous layer) which derives from the conjunctival goblet cells, as well as some secretion from the lacrimal gland. (2) The watery lacrimal fluid is the middle layer, called the lacrimal (or aqueous layer). It is secreted by the lacrimal gland and the accessory glands of Krause and Wolfring. It forms the bulk of the film and contains most of the bactericidal lysosyme and other proteins, inorganic salts, sugars, amino acids, urea, etc. (3) The oily layer (or lipid layer) is the most superficial and is derived principally from the meibomian glands in the lids as well as some secretion from the glands of Zeis. It greatly slows the evaporation of the watery layer and may provide a lubrication effect between lid and cornea (Fig. F6). Note: Some authors have suggested that the precorneal film is made up of only two layers; an innermost aqueous and mucin gel layer and an outer lipid layer. Syn. lacrimal layer; preocular tear film; tear film; tear layer. See hyperlacrimation; mucin; tear secretion; Tearscope; break-up time test.
Fig. F6 Diagram of the three layers of the precorneal film attached to the squamous epithelial cellsenlarge picture
Fig. F6 Diagram of the three layers of the precorneal film attached to the squamous epithelial cells
References in periodicals archive ?
Fed by a tear duct, dyed blue, the eyelid spreads artificial tear secretions over the eye to form what is called a tear film.
Asked what steps he takes to prevent dry eye developing in contact lens wearers, Mr Howard highlighted the importance of using corneal topography to assess tear film quality and consistency.
DES is a disorder where loss of homeostasis of the tear film results in pain, itching, blurry vision, and dryness, among other symptoms.
Tear film stability is the most important indicator of tear film (dys)function (1).
A healthy ocular surface and a stable tear film are essential to
In preclinical studies, the AMPPLIFY technology increased delivery of loteprednol etabonate into ocular tissues more than three-fold compared to current LE products by facilitating penetration through the tear film mucins.
Alcon, the global leader in eye care and a division of Novartis, today announced that it has acquired Tear Film Innovations, Inc.
"For example, we found that interference from biomolecules in tears resulted in challenges in obtaining accurate glucose readings from the small quantities of glucose in the tear film. "In addition, our clinical studies have demonstrated challenges in achieving the steady state conditions necessary for reliable tear glucose readings," Otis added.
According to the 2017 International Dry Eye Workshop II (DEWS II) report, dry eye is "a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles." (1) Typical clinically severe dry eye disease manifests with symptoms such as restriction of daily activities, pain, decreased wellness, and impairment in general health.
New Freshkote PF is designed to support the integrity of all three layers of the eye's tear film, offering dry eye patient's relief from their symptoms.
According to the company, the new FRESHKOTE PF is designed to support the integrity of all three layers of the eye's tear film, offering dry eye patient's relief from their symptoms.
The device, called the NuLids System, works by gently stimulating and rejuvenating the glands, resulting in improved tear film stability, comfort, and lubrication.