ANATOMY - CONJUNCTIVA

Question 1

What are the 3 types of conjunctiva? Subtypes?

Answer 1

Palpebral (inner eyelid) - marginal, tarsal, orbital
Bulbar (anterior eyeball) - scleral, limbal
Forniceal (in between both)

Question 2

Where is the conjunctiva firmly adherent to? Where is the conjunctiva loosly attached to?

Answer 2

Adherent to lids over tarsal plates (upper > lower)
Loosely attached to fornices and over globe (except limbus)

Question 3

1. What is the sulcus subtarsalis?
2. How far is it away from lid margin?
3. When is the subtarsalis scarred?

Answer 3

1. Groove 2mm away from lid margin
2. 2mm - common site for foreign body lodging
3. Trachoma - Arlt’s line

Question 4

What are the different structures in the palpebral conjunctiva?

Answer 4

1. Marginal conjunctiva (anterior - posterior lid margin)
2. Sulcus Subtarsalis
3. Tarsal Conjunctiva (covers tarsal plate)
4. Orbital Conjunctiva (between tarsal plate and fornix, over muller’s muscle)

Question 5

What are the types of epithelium in the conjunctiva?

Answer 5

Marginal - 5 layers of non keratinised stratified squameous epithelium

Tarsal - 2 layers of stratified cuboidal epithelium

Fornix/bulbar - 3 layers of stratified squamous epithelium

Limbal - 10 layers of stratified squamous epithelium

WAY TO REMEMBER: 5 + (2 + 3 ) = 10

Question 6

What is the main property of forniceal conjunctiva?

Answer 6

Thicker conjunctiva and is loosely present to allow movement of globe

Question 7

How much tear fluid is present in the conjunctival sac?

Answer 7

7 microlitres, can hold up to 30 microlitres

Question 8

Where is the bulbar conjunctiva firmly adherent (2 places)

Answer 8

1. 3mm zone near limbus
2. Insertion of rectus muscles

Question 9

What happens to the conjunctival epithelium when goes from fornices to the limbus?

Answer 9

Becomes thicker

Question 10

What is the pathological mechanism of squamous metaplasia of the conjunctiva?

Answer 10

transition of squamous, moist non-keratinised to become dry, keratinised epithelium

The lid margins are covered anteriorly by dry, keratinised epithelium which mergies into moist non keratinised epithelium in the tarsus. In many ocular surface disorders, the change of normal epithelium to become non-secretory and keratinised (sqameous metaplasia)

Question 11

What are the side effects of topical drugs on the conjunctiva?

Answer 11

look at diagram.

Question 12

What is the function of the goblet cells ? (2) Where are they located (1)

Answer 12

Secrete 2.2ml of mucin

Ensure stability of tear film by decreasing surface tension

Located throughout the conjunctival epithelium and arise from basal layer

Question 13

What are the layers of the conjunctiva?

Answer 13

1. Epithelium
2. Adenoid/Lymphoid Layer
3. Fibrous Layer

Question 14

What are the structures within the adenoid/lymphoid layer of conjunctiva? (3)

Answer 14

1. Lymphoid tissue (follicles are formed)
2. Mast cells (6000 per mm cubed)
3. Plasma cells, lymphocytes, neutrophils (CALT - conjunctival associated lymphoid tissue)

Question 15

When does the lymphoid/adenoid layer of the conjunctiva arise?

Answer 15

3-4 months old

Question 16

What is the structure of the fibrous layer of the conjunctiva?

Answer 16

Connective tissue which attaches to tarsal plate - contributes to papillae

Question 17

Where are the Popov glands located?

Answer 17

Located within the substance of the caruncle

Question 18

How many Krause /Wolfring glands are there?

Answer 18

Krause - 20-40 in upper fornix, 6-8 in lower fornix

Wolfring - 2-5 located along superior tarsal border

Question 19

What are the accessory lacrimal glands? What is their role?

Answer 19

Krause, Wolfring, Popov

1. Contribute 10% of lacrimal secretions
2. Contribute to basal tear secretion, no contribution to reflex tear secretion

Question 19

What supplies the palpebral conjunctiva? What supplies the bulbar conjunctiva?

Answer 19

Palpebral : marginal arcade (marginal) and peripheral arcade (forniceal + orbital + tarsal)

Bulbar:
1. anterior conjunctival artery (branch of anterior ciliary for limbus)
2. posterior conjunctival artery (branch of peripheral arcade)

Question 19

What does the conjunctiva drain into ? What does the limbus drain into?

Answer 19

Superior and inferior ophthalmc veins from eyelid plexus
Limbus –> anterior ciliary vein

Question 20

What is the nerve supply of the conjunctiva?

Answer 20

1. Superior Palpebral and forniceal - V1 (lacrimal and frontal branches)
2. Inferior palpebral and forniceal - V1 and V2 (lacrimal branches and infraorbital nerve)
3. Bulbar : long ciliary nerve (nasociliary nerve - V1)

Question 21

What is the function of the conjunctiva? (4)

Answer 21

1. Tear production (mucin by goblet cells, aqueous by accessory lacrimal glands
2. Supply of oxygen directly to cornea when eye is open
3. Wash off debris and maintain smooth ocular surface
4. Protection of eye by defense mechanisms - secretory IgA, mucin clumping, mast cell outpouring, intact epithelial barrier, lacrimation

Question 22

Where are the goblet cells most abundant?

Answer 22

Fornices and plica semilunaris

Question 23

Which nutrients are the most essential for health of conjunctival epithelium and goblet cells?

Answer 23

retinoids and vitamin A

Question 24

Where do the lymphatics drain laterally and medially?

Answer 24

Laterally : superficial parotid nodes
Medially: submandibular nodes

Question 25

Epithelial basement membrane of the conjunctiva is composed of which type of collagen?

Answer 25

Type IV

Question 26

The lateral fornix of the conjunctiva extends how far from the limbus to the equator?

Answer 26

14mm

Question 27

In primary gaze position, where does the upper lid and lower lid cover in relation to the cornea?

Answer 27

upper lid : covers 1/6th of cornea
lower lid: covers inferior limbus

Question 28

Where does the lateral canthus lie in relation to the lateral orbital margin?

Answer 28

5-7mm