Review of clinical anatomy and physiology of the conjunctiva Ayesha S Abdullah 20.09.2013

Review of clinical anatomy and physiology

of the conjunctiva

Ayesha S Abdullah

20.09.2013

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By the end of this lecture the students would be able to;

Correlate the structural organization of the conjunctiva with its functions

Identify important anatomical landmarks on conjunctival photographs and histological photomicrographs.

Relate the clinical presentation of conjunctival disorders with the structural organization and physiological functions of the conjunctiva

Learning outcome

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Let us look at a case

A 25 year old young man presented to the OPD with the complaints of watering of both the eyes with a feeling of grittiness and foreign body sensation for the last 03 years. He also had gradual visual loss of vision. His symptoms worsened over the years. He had a history of chemical injury to his eyes 03 years ago.

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What questions come to your mind? Why the feeling of grittiness and foreign

body sensation in the eyes? Why the gradual visual loss? What keeps the ocular surface

moistened? When we look around in different

directions why don’t we get the feeling of the ocular surface beneath the eyelids and in front of the eye rubbing against each other?

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Some more questions What is conjunctiva? A mucous membrane covering the under

surface of the lids and anterior part of the eyeball upto the cornea

Histologically what are the layers of the conjunctiva?

Epithelium Submucosa/stroma/substantia propria What kind of epithelium should the

conjunctiva have? Stratified epithelium Why? Exposed ocular surface, vulnerable to subtle

trauma excessive movement of the eye and rubbing

of the surfaces

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What keeps the conjunctiva moist & lubricated?

Tear film Which type of secretary cells and glands

are responsible for this function? Goblet cells and accessory lacrimal glands Where are these cells located? Throughout stratified columnar epithelium What else is there in the submucosa? Outer lymphoid layer; macrophages, mast cells,

polmorphs, eosinophils and aggregates of lymphocytes, IgA

Inner fibrous layer; collagen fibers, blood vessels, fibroblasts and accessory lacrimal glands

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What are follicles?

Aggregates of lymphoid tissue with in the submucosa/substantia propria

A reaction to infections or hypersensitivity response

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What are papillae?

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Hyperplastic conjunctival epithelium with central core vessel surrounded by infiltrate separated from each other by fibrous septa- seen in allergic & bacterial conjucntvitis

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Topographically, what are the different parts of the conjunctiva?

Palpebral Bulbar Forniceal (fornix) Plica semilunaris & caruncle

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Limbus

Bulbar conjunctiva

Forniceal conjunctiva

Tarsal conjunctiva

Marginal conjunctiva

Plica semilunaris & Caruncle

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Should the epithelium be the same or different in different parts of the conjunctiva?

It should be different Stratified columnar epithelium 2 – 5 cells. At limbus change into stratified squamous non

keratinized epithelium. At lid margin non keratinized stratified

squamous epithelium changes into keratinized stratified squamous epithelium

Why? Different role of each part

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Should it be keratinized or non-keratinized? Why?

Non-keratinized to aid maintenance of smooth surface, less friction during ocular and lid movements

What keeps it non-keratinized? Normal ocular surface environment Vitamin A When could it get keratinized? what

would happen?

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Limbus

Bulbar conjunctiva

Forniceal conjunctiva-crypts of Henle

Tarsal conjunctiva

Marginal conjunctiva

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stratified squamous epithelium with few goblet cells

focal surface keratinization

hair follicles (arrow 12), sebaceous glands (arrow 13) and adipose tissue (arrow 15).

Plica semilunaris

Caruncle

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Clincially it appears like this

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What is the blood supply of the conjunctiva?

Why is it so richly supplied with blood vessels?

Which general physical examination draws from the rich pink colour of the palpebral conjunctiva?

What unconventional role do conjunctival blood vessels perform?

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CILIARY CONGESTIONCONJUNCTIVAL CONGESTION

Blood supply

Arterial supply; Posterior conjunctival arteries derived from

arterial arcade of lids which is formed by palpebral branches of nasal and lacrimal arteries of the lids.

Anterior conjunctival arteries derived from the anterior ciliary arteries – muscular br. of ophthalmic artery to rectus muscles.

Venous drainage; Palpebral and Ophthalmic veins.

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Should there be a nerve supply? What kind? Name the nerves? Should there be lymphatic drainage? Where would the lymphatics drain? If the lymph nodes are palpable/enlarged

what is it called? What does lymphadenopathy signify?

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PHYSIOLOGY Smooth surface. Secretes mucin and aqueous component

of tear film. Highly vascular: supplies nutrition to the

peripheral cornea. Aqueous veins drains from anterior

chamber maintenance of IOP. Lymphoid tissue helps in combating

infections. Basic secretion—reflex secretion.

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Summarize

How is conjunctiva organized structurally?

What are major functions of conjunctiva? Protection –physical, immunological Smooth and healthy ocular surface Nourishment for the lids and cornea Role in aqueous drainage Smooth, controlled and free ocular

movements.

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Summarize

How does the structure and function correlate with the clinical symptoms and signs?

Discharge, watering Dry eyes Follicles and papillae Anemia Jaundice , would you be able to see it if

the conjunctiva were opaque? Lymphadenopathy Tumours and cysts