Lacrimal Gland
The main lacrimal gland is located in a shallow depression within the orbital part of the frontal bone. The gland is separated from the orbit by fibroadipose tissue and is divided into 2 parts, orbital and palpebral lobes, by the lateral horn of the levator aponeurosis (Fig 1-38). When the upper eyelid is everted, the smaller palpebral lobe can be seen in the superolateral conjunctival fornix. An isthmus of glandular tissue may exist between the palpebral lobe and the larger orbital lobe.
A variable number of thin-walled excretory ducts, blood vessels, lymphatics, and nerves pass from the orbital lobe into the palpebral lacrimal gland. The ducts continue downward, and about 12 of them empty into the conjunctival fornix approximately 5 mm above the superior margin of the upper tarsus.
The lacrimal glands are exocrine glands that produce a serous secretion. The body of each gland contains 2 cell types (Fig 1-39):
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glandular epithelial cells, which line the lumen of the gland
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myoepithelial cells, which surround the parenchyma and are covered by a basement membrane
Lacrimal secretions comprise the aqueous component of the tear film and include lysozymes, lactoferrin, and immunoglobulin A. The lacrimal gland undergoes structural and functional alterations with age, which may play a role in acquired dry eye.
The lacrimal artery, a branch of the ophthalmic artery, supplies the gland with blood. The lacrimal gland receives secretomotor cholinergic, vasoactive intestinal polypeptide (VIP)-ergic, and sympathetic nerve fibers in addition to sensory innervation via the lacrimal nerve (from CN V1). The gland’s extremely complex neuroanatomy governs both reflex and psychogenic stimulation (see BCSC Section 5, Neuro-Ophthalmology).
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Rocha EM, Alves M, Rios JD, Dartt DA. The aging lacrimal gland: changes in structure and function. Ocul Surf. 2008;6(4):162–174.
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.