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Anatomy & histology-other

Author: Nat Pernick, M.D.

Last author update: 1 February 2014

Last staff update: 3 December 2024 (update in progress)

Copyright: 2004-2025, PathologyOutlines.com, Inc.

PubMed Search: Anatomy [title] eye

Table of Contents

Cite this page: Pernick N. Anatomy & histology-other. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/eyeanatomyother.html. Accessed January 10th, 2025.

Globe

Defined as eyeball itself plus intraocular tissues, or eye proper without its appendages
Dimensions: anterior-posterior 24 mm, vertical and horizontal dimensions are both 23 to 23.5 mm
Six extraocular muscles:
- 4 rectus and 2 oblique muscles
- Arise in posterior orbit from fibrous ring called annulus of Zinn, and insert into sclera
- Muscles are surrounded by fascia
- Inferior oblique inserts on sclera, other muscles insert on tendons
Equator: midway between anterior and posterior poles
Specimen is the result of enucleation, performed because eye is nonfunctional, painful, unsightly, infectious, contains neoplasm, post-trauma (may be removed to prevent sympathetic uveitis) or has chronic glaucoma
Globe usually intact but free of extraocular muscles and orbital fat
Globe may be eviscerated, with only fragments available for microscopic study
Initial pathologic processes may be obscured by subsequent pathologic processes
Enucleation: due to tumor (48%, usually melanoma), glaucoma (13%), phthisis bulbi (12%), recent trauma (11%)
Specimens also received after evisceration (10%) or exenteration (9%) to manage malignant orbital tumors (Am J Clin Pathol 2003;119:594)
During 1990 to 2000, decrease in percentages due to neoplasms, increase due to glaucoma and phthisis bulbi

Lacrimal duct & gland

Lacrimal gland located in superiotemporal aspect of orbit, not palpable
Contributes secretions to tear film including IgA
Accessory lacrimal glands are embedded above fibrous tarsus of eyelid and in conjunctival fornix
Serous with minor mucinous component
Larger ducts have myoepithelial layer
Normally may have lymphocytes and plasma cells
Drainage apparatus is composed of puncta, canaliculi, lacrimal sac and nasolacrimal duct
Tears drain toward medial canthus, then through lacrimal punctum into lacrimal canaliculi, then nasolacrimal sac, then nasolacrimal duct, then nose
Puncta:
- Opening in medial aspect of eyelid where tear fluid drains
Canaliculi (lacrimal duct):
- Tubular structures 0.5 mm in diameter where puncta drains
- Nonkeratinizing squamous epithelium surrounded by fibrous tissue
Lacrimal sac:
- Merging of canaliculi, encased by bones of orbit
- Stratified columnar epithelium with goblet cells
Nasolacrimal duct:
- Drains lacrimal sac, 1 cm long, connects to inferior meatus of nose
- Stratified columnar epithelium with goblet cells
Lacrimal duct disorders often cause epiphora (tears flow over lid margin onto cheek), induration, inflammation of lower eyelid
Tumors tend to displace eye downward because adjacent orbit restricts growth
Tumors are difficult to resect completely leading to high recurrence rate
Lacrimal gland is considered a minor salivary gland for tumor reporting
Regional lymph nodes are preauricular (parotid), submandibular and cervical

Lens

Most surgical specimens are cataracts or prosthetic intraocular lens
Normal lens is biconvex, behind pupil / iris, in front of vitreous, in posterior chamber
10 mm in diameter by 4 - 5 mm in width
Usually Gross Examination Only (report as transparent - Yes or No), don't section
Anterior lens capsule is eosinophilic acellular band overlying single layer of epithelial cells
Lens capsule is strongly PAS+, holds lens in place
Lens has thinner capsule posteriorly, without epithelial cells
Lens in held in place by zonules that connect to pars plicata of ciliary body
Lens normally opacifies with age due to globules of degenerate lens fibers
Is a closed epithelial system with lens capsule (epithelium) that totally envelops the lens
Vitreous humor:
- Avascular
- Extends from lens to sensory retina
- Contains gel-like material composed of water, protein, hyaluronic acid and "hyalocytes"
- Gel consistency is due to randomly oriented collagen fibrils
- May appear as amorphous material on H&E

Orbit & optic nerve

Orbit contains globe and its fibrous covering (Tenon capsule), lacrimal gland, optic nerve and its meningeal covering, extraocular muscles, cartilaginous trochlea, blood vessels and delicate fibroadipose connective tissue
Floor of orbit is roof of maxillary sinus
Medial wall of orbit (lamina papyracea) separates orbit from ethmoidal sinuses
Proptosis: forward displacement of eyeball (or other organs), due to any disease that increases orbital contents, since orbit is closed medially, laterally and posteriorly
Exophthalmos: abnormal protrusion of eyeball
- Common symptom of orbital disease, although often due to thyroid disease and not biopsied
- Other common causes of exophthalmos are mucocele from paranasal sinus, hemangioma, inflammatory pseudotumor
Optic nerve:
- Surrounded by meninges; part of central nervous system
- Not usually biopsied
- Often has psammoma bodies or drusen (calcified acellular globular concretions of nerve fibers)
- Site of convergence of one million axons from retinal nerve fiber layer
- Nerve head accounts for physiologic blind spot in normal visual field
- Receives blood supply from branches of ophthalmic artery
- Surrounded on both sides by short posterior ciliary arteries
Lamina cribrosa:
- Site of myelination of optic nerve axons
- Highlighted with Luxol fast blue or other myelin stains
Trochlea:
- Arc shaped structure through which tendon of superior oblique muscle passes before insertion upon eyeball
- The only cartilaginous structure in normal orbit
Tumors should be reported using formats published for their counterparts elsewhere in body
Drainage through submandibular, parotid and cervical lymph nodes through vascular anastomosis