ANATOMY - ANGLE

Question 1

What are the borders of the anterior chamber?

Answer 1

ANTERIOR : posterior cornea
POSTERIOR: anterior iris

Question 2

How deep is the anterior chamber?

Answer 2

3mm

Question 3

Is the anterior chamber shallower in hypermetropes or myopes?

Answer 3

Shallower in hypermetropes - Axial length is smaller

Question 4

How much aqueous humor is present in the anterior chamber?

How much aqueous humor is present in posterior chamber?

Answer 4

0.25ml

0.06ml

Question 5

What are the structures of the angle of the anterior chamber? (6)

Answer 5

1. Iris Root
2. Ciliary Body
3. Scleral Spur
4. Trabecular meshwork (posterior/pigmented)
5. Trabecular meshwork (anterior/not-pigmented)
6. Schwalbe’s line

I CAN SEE TILL SCHWALBE’S LINE

Question 6

What is the scleral spur

Answer 6

At the junction of the limbus, internally there is a groove/indendation called the scleral sulcus.
A projection posterior from this area and is called the scleral spur

Question 7

What is the ciliary body band?

Answer 7

Ciliary body is attached to scleral spur - a space exists here called the supraciliary space bewteen the ciliary body and sclera

Iris inserts into anterior side of ciliary body, and part of the ciliary body between iris and scleral spur is ciliary band, which is seen on gonioscopy

Question 8

What is Schlemm’s Canal?

Answer 8

A Continuation of trabecular meshwork as a canal - it is oval in shape and is lined by non-fenestrated endothelium

It is perforated by aqueous collector channels which branch into intrascleral and deep scleral plexi

Question 9

What is Schwalbe’s line

Answer 9

Trabecular meshwork inserts into the periphery of the cornea at a ridge, known as Schwalbe’s line - marks the end of Descemet’s membrane of the cornea

Most anterior structure of gonioscopy

Question 10

What is posterior embryotoxon?

Answer 10

Anterior displacement of Schwalbe’s line which is prominent on external exmination - associated with eisenfeld riger syndrome

Question 11

What is Sampaoelsi’s line?

Answer 11

Pigmented Schwalbe’s line seen in PXF and pigment dispersion syndrome

Question 12

What are the main age related changes seen in the trabecular meshwork? (5)

Answer 12

1) Increased pigmentation
2) Increased debris accumulation
3) Increased glycosaminoglycan deposition in extracellular space
4) Thickened basement membrane
5) Reduced endothelial cells

Question 13

What are the three layers of the trabecular meshwork? Which layer has the least resistance? Which layer has the most resistance to outflow?

Answer 13

1. Uveal meshwork (inner) - least resistance
2. Corneoscleral meshwork (middle) - lamellar strtucture of connective tissue covered by endothelium like cells
3. Cribiform/juxtacanalicular (outermost) - most resistance embedded in an extracellular matrix

Question 14

What is the function of the trabecular cells that line the passageways (2)

Answer 14

1. Dehydrate connective tissue (similar to corneal endothelium)
2. Phagocytic properties to collect debris

Question 15

Whats the difference between conventional outflow and non-conventional outflow?

Answer 15

Conventional outflow (70%) - through Schlemms canal

Uveoscleral (30%) - through ciliary body muscle fibres into suprachoroidal space and into sclera and venous system

Question 16

What happens to flow after contract of the ciliary muscle?

Answer 16

Contraction of ciliary muscle causes expansion of trabecular meshwork structure, resulting in enlargement of the intertrabecular spaces and redcued resistance to aqueous outflow

Question 17

Diagram of angle structures.

Answer 17

Question 18

What is the drainage pathway of aqueous humour from the canal of schlemm?

Answer 18

Canal of Schlemm —> collector channel —> deep scleral venous plexus —> intrascleral plexus —> anterior ciliary veins

Question 19

What is the rate of production of the aqueous humour?

Answer 19

3 microlitres per minute.