by BodyScientific
Understanding
DRY EYE DISEASE
Model You Scanned
OYSTER FACE ANATOMY MODEL OP-TYR-000568
The parasympathetic nervous system, the "rest and digest" system of the body, controls tear film homeostasis partially via the trigeminal nerve, which is accessible within the nose. This anatomy face model demonstrates the connection of the parasympathetic nervous system from sensory nerves in the nasal glands and its direct connection to the 3 major players of tear film production; the conjunctiva, meibomian glands, and lacrimal gland.
Overall dimensions on base: 6.75 x 6.5 x 4.5 inches.
What is Dry Eye Syndrome?
A healthy tear film lubricates and protects the eyes from injury and infection, washes away foreign particles, and contributes refractive power for clear vision.
Dry eye occurs when tears aren't able to provide adequate moisture. Your eyes may also be prone to bacterial infections, or the surface of your eyes may become inflamed.
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Signs and symptoms:
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There is a scratchy or gritty feeling like something is in your eye
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Blurred vision, especially when reading
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Mucus discharge
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Ocular irritation
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It is painful to wear contact lenses
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Excessive tearing (secondary to reflex secretion)
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Photophobia
Normal Eye Anatomy
The Tear Film Glands
Every few seconds the eyelids blink, recoating the outer surface of the cornea and conjunctiva with a tear film. This tear film lubricates the eye, removes old cells and foreign bodies. It protects the eye from irritation and promotes good eye health. Tear film is primarily produced by the lacrimal and meibomian glands.
The Lacrimal Gland
The lacrimal gland is the largest tear-producing gland. It is located above and along the outer rim of the eye. Lacrimal gland excretory ducts open on the inner surface of the upper eyelid. The lacrimal gland is the major producer of tears, and releases tear fluid regularly to lubricate the eye, and as a reflex response to emotions (crying) or a foreign body irritation. The primary component of the fluid from the lacrimal gland is aqueous.
The Meibomian Glands
The meibomian glands are long, thin sebaceous glands within the upper and lower eyelids. They produce the lipid lubricant fluid called sebum, which is excreted through tiny ducts along the edges of the eyelids. This fluid keeps the aqueous layer from evaporating easily. Other sebaceous glands that contribute to the tear film are the Glands of Wolfring, Moll and Zeis.