There's Nothing Fishy About Omega-3 Fatty Acids for Dry Eye Syndrome
Dry eye syndrome (DES) is a common affliction that presents to the ophthalmologist. The ocular discomfort, burning, stinging, vision blurring, and other symptoms affect more than 7.5% of US men age 80 years and older and nearly 10% of US women age 75 years and older. These symptoms measurably affect activities of daily life, such as reading, using a computer, driving, and watching television.
DES is a multifactorial disease that has, at its essence, some deficiency or abnormality of the ocular tear film. The tear film has 3 main layers.
The first layer is a superficial layer of lipids approximately 0.1 ÎĽm thick. This hydrophobic, oily layer is primarily produced by the meibomian glands, and its chief function is to reduce evaporation of the underlying aqueous layer.
The second and thickest layer is the aqueous layer. It is approximately 7 ÎĽm thick. The aqueous layer is produced by the main and accessory lacrimal glands. It hydrates the ocular surface and provides a smooth refractive surface for light entering the eye.
The final, thinnest layer is the mucin layer. Approximately 0.05 ÎĽm thick, this layer is produced by the goblet cells in the conjunctiva. Its lipophilic properties allow it to spread evenly over the epithelial membranes of the ocular surface. The mucin layer also has hydrophilic properties, allowing the overlying aqueous layer to spread evenly over it.
DES is most commonly thought to be due to aqueous tear deficiency as a result of insufficient aqueous tear production. Age plays a role in aqueous tear deficiency, with decreased production of aqueous tears and atrophy of the lacrimal glands occurring with age, especially in postmenopausal women. Another dominant cause of DES is evaporative dry eye, where the lipid layer cannot sufficiently inhibit the aqueous layer from evaporating. A meibomian gland dysfunction is usually present in evaporative dry eye. Both entities (aqueous tear deficiency and evaporative dry eye) result in increased osmolarity of the tear film and subsequent inflammation of the aqueous surface.
Mucin abnormalities may occur in cases such as chemical injury to the eye or in diseases such as Steven-Johnson syndrome. With a poor mucin layer, the overlying aqueous layer cannot adequately cover the ocular surface, leading to epithelial damage from dessication.
Dry Eye Syndrome: Background, Prevalence, and Causes
Background and Prevalence of Dry Eye Syndrome
Dry eye syndrome (DES) is a common affliction that presents to the ophthalmologist. The ocular discomfort, burning, stinging, vision blurring, and other symptoms affect more than 7.5% of US men age 80 years and older and nearly 10% of US women age 75 years and older. These symptoms measurably affect activities of daily life, such as reading, using a computer, driving, and watching television.
DES is a multifactorial disease that has, at its essence, some deficiency or abnormality of the ocular tear film. The tear film has 3 main layers.
The first layer is a superficial layer of lipids approximately 0.1 ÎĽm thick. This hydrophobic, oily layer is primarily produced by the meibomian glands, and its chief function is to reduce evaporation of the underlying aqueous layer.
The second and thickest layer is the aqueous layer. It is approximately 7 ÎĽm thick. The aqueous layer is produced by the main and accessory lacrimal glands. It hydrates the ocular surface and provides a smooth refractive surface for light entering the eye.
The final, thinnest layer is the mucin layer. Approximately 0.05 ÎĽm thick, this layer is produced by the goblet cells in the conjunctiva. Its lipophilic properties allow it to spread evenly over the epithelial membranes of the ocular surface. The mucin layer also has hydrophilic properties, allowing the overlying aqueous layer to spread evenly over it.
Causes of Dry Eye Syndrome
DES is most commonly thought to be due to aqueous tear deficiency as a result of insufficient aqueous tear production. Age plays a role in aqueous tear deficiency, with decreased production of aqueous tears and atrophy of the lacrimal glands occurring with age, especially in postmenopausal women. Another dominant cause of DES is evaporative dry eye, where the lipid layer cannot sufficiently inhibit the aqueous layer from evaporating. A meibomian gland dysfunction is usually present in evaporative dry eye. Both entities (aqueous tear deficiency and evaporative dry eye) result in increased osmolarity of the tear film and subsequent inflammation of the aqueous surface.
Mucin abnormalities may occur in cases such as chemical injury to the eye or in diseases such as Steven-Johnson syndrome. With a poor mucin layer, the overlying aqueous layer cannot adequately cover the ocular surface, leading to epithelial damage from dessication.
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