L19 - Conjunctiva

Question 1

What are the three main regions of the conjunctiva?

Answer 1

Bulbar conjunctiva, palpebral conjunctiva, fornix.

Question 2

What are the three parts of the palpebral conjunctiva?

Answer 2

Marginal part, tarsal part, orbital part.

Question 3

Where does the marginal part of the palpebral conjunctiva extend?

Answer 3

From the lid margin (opening of tarsal gland) to the sulcus subtarsalis.

Question 4

What is the sulcus subtarsalis?

Answer 4

A shallow groove situated 2mm from the lid margin, marking the inferior edge of the tarsal plate.

Question 5

Where do the lacrimal puncta open?

Answer 5

In the marginal zone of the palpebral conjunctiva.

Question 6

What are features of the tarsal part of the palpebral conjunctiva?

Answer 6

Very vascular, adherent to the tarsal plates, more adherent in upper eyelid, Meibomian glands visible as yellow lines, nasal tarsal conjunctiva contains Henle’s mucus crypts.

Question 7

What are papillae and follicles in the tarsal conjunctiva?

Answer 7

Papillae (upper lid) are composed of chronic inflammatory cells; follicles (lower lid) are identical to lymphoid follicles found elsewhere in the body.

Question 8

What is the orbital part of the palpebral conjunctiva?

Answer 8

Loosely covers between the tarsal plate and fornix, thrown into horizontal folds during eye movements, lies over Mueller’s muscle in upper lid, has Stieda’s plateaux and grooves.

Question 9

What is the function of the conjunctival fornices?

Answer 9

Join the bulbar and palpebral conjunctiva, allow free movement of the globe, and receive ducts of the lacrimal gland in the lateral part of the superior fornix.

Question 10

What are the approximate dimensions of the conjunctival fornices?

Answer 10

8-10mm (superior), 7mm (inferior), 8-10mm (temporal), 14mm (nasal).

Question 11

What are features of the bulbar conjunctiva?

Answer 11

Thinnest part, transparent so underlying sclera and vessels are seen, loosely attached except near limbus (3mm zone) and rectus muscle insertions, limbal conjunctiva fuses with corneal epithelium.

Question 12

What are the three layers of conjunctival histology?

Answer 12

Epithelium, adenoid layer (lymphoid layer), fibrous layer.

Question 13

What is the structure of the marginal conjunctival epithelium?

Answer 13

5-layered non-keratinised, stratified squamous epithelium (superficial squamous, middle polyhedral, deepest cylindrical cells).

Question 14

What is the structure of the tarsal & orbital conjunctival epithelium?

Answer 14

2 layers of stratified cuboidal epithelium (superficial cylindrical, deepest cuboidal cells).

Question 15

What is the structure of the fornix & scleral conjunctival epithelium?

Answer 15

3 layers of stratified squamous epithelium (superficial cylindrical, middle polyhedral, deepest cuboidal cells).

Question 16

What is the structure of the limbal conjunctival epithelium?

Answer 16

10 layers of stratified squamous epithelium (superficial squamous, middle polygonal, basal cuboidal cells).

Question 17

Which cells are found in the conjunctival epithelium?

Answer 17

Goblet cells, melanocytes, Langerhan’s cells, CALT (conjunctiva-associated lymphoid tissue), MALT (mucosa-associated lymphoid tissue).

Question 18

What is the function of goblet cells in the conjunctiva?

Answer 18

Produce mucous component of the tear film; absent in marginal and limbal conjunctiva; destroyed after discharging content.

Question 19

Where is goblet cell density highest?

Answer 19

Nasally, and in children and young adults.

Question 20

What can reduce goblet cell density?

Answer 20

Glaucoma therapy.

Question 21

What is the adenoid layer of the substantia propria?

Answer 21

A lymphoid layer with fine connective tissue reticulum and lymphocytes; not present at birth (develops after 2-4 months); contains mast cells.

Question 22

What is the fibrous layer of the substantia propria?

Answer 22

Contains collagenous and elastic fibres; thicker than adenoid layer except in the tarsal conjunctiva; lodges conjunctival vessels and nerves.

Question 23

Name the conjunctival mucin glands.

Answer 23

Goblet cells, Henle’s glands, glands of Manz.

Question 24

Name the accessory lacrimal glands of the conjunctiva.

Answer 24

Glands of Krause, glands of Wolfring.

Question 25

What is the plica semilunaris conjunctivae?

Answer 25

A crescent-shaped fold of conjunctiva at the medial canthus; remnant of the nictitating membrane; allows full lateral movement without tissue stretching.

Question 26

What is the caruncle?

Answer 26

A mound of tissue overlying the medial edge of the plica semilunaris; contains non-keratinized epithelium and accessory glands (like conjunctiva), as well as hair follicles, sebaceous and sweat glands (like skin).

Question 27

What is the function of the caruncle?

Answer 27

Poorly understood.

Question 28

What are the three main arterial sources for conjunctival blood supply?

Answer 28

Marginal tarsal arcade, peripheral tarsal arcade, anterior ciliary arcade.

Question 29

What is the venous drainage of the conjunctiva?

Answer 29

More numerous than arteries, accompany arteries, drain into venous complex of eyelids and superior/inferior ophthalmic vein, circum-corneal zone drains into anterior ciliary veins.

Question 30

How is conjunctival lymph drainage organized?

Answer 30

Divided into superficial and deep parts; lateral side drains to preauricular (superficial parotid) nodes, medial side drains to submandibular lymph node.

Question 31

Which nerves supply the conjunctiva?

Answer 31

Superior tarsal conjunctiva, bulbar conjunctiva, inferior tarsal conjunctiva, supraorbital nerve, circum-corneal zone (long ciliary nerves), supratrochlear nerve, infratrochlear nerve, infraorbital nerve, lacrimal nerve.

Question 32

What age-related changes occur in the conjunctiva?

Answer 32

Epithelial cells change from square to vertically elongated, decrease in height and number of layers, decrease in collagen, easier movement of conjunctival flap, blood vessels in bulbar conjunctiva become more random and fragile.