1.05 Ciliary body, aqueous humour and IOP

Ciliary body function

Produce aqueous

Contains ciliary muscle to change shape of the lens (via zonules)

Label the posterior iris

1. Ciliary processes

2. Fibres of suspensory ligaments

3. Striae in pars plana

4. Ora serrata

5. Peripheral cystic degeneration

How is the ciliary body attached to the iris and lens

Via zonules

Label

1. Vitreous humor

2. Sclera

3. Ciliary body

4. Canal of schlemm

5. Aqueous humor

6. Iris

7. Posterior chamber

8. Corne

9. Anterior chamber

10. Pupil

11. Lens

What is the thickest part of the ciliary body

Anterior pars plicta (closest to lens)

This gets thinner as you get more posterior

Where is the pars plana

Runs up to the edge of the retina

Where is the ora serrata

Edge of the retina

What are the two part of the ciliary body and how do they differ

Pars plicata - wider, naterior portion containing the ciliary processes

Pars plana - flatter region. It extends from the posterior of the pars plicata to the ora serrata (which is the transition between ciliary body and choroid)

Label

1. Lens

2. Zonules

3. Pars plicata

4. Pars plana

Label

1. Non pigmented epithelium

2. Pigmented epithelium

3. Supraciliaris

4. Ciliary muscle

5. Ciliary stroma

6. Pars plana

7. Pars plicata

Label the ciliary muscle

1. Meridional portion

2. Radial portion

3. Circular portion

Layers of the ciliary body

Label the layers of the ciliary body

1. Supraciliaris

2. Ciliary muscle

3. Ciliary stroma/pigmented epithelium

4. Non pigmented epithelium

Supraciliaris

• tissue

• Type

• Function

• tissue - connective (collagen)

• Type - loose/ fibroblasts and melanocytes

• Function - loose interface with sclera - passage of nerves and blood vessels

Ciliary muscle

• tissue

• Type

• Function

• tissue - muscle

• Type - smooth muscle (involuntary)

• Function - controls accomodation

Ciliary stroma

• tissue

• Type

• Function

• tissue - connective

• Type - loose

• Function - supporting framework for muscle and blood vessels

Ciliary epithelium pigmented

• tissue

• Type

• Function

• tissue - inner epithelium

• Type - pigmented, simple, cuboidal

• Function - light absorption in posterior cavity, helps the production of aqueous humor

Ciliary epithelium unpigmented

• tissue

• Type

• Function

• tissue - epithelium

• Type - unpigmented simple

  • Pars plicata - cuboidal

  • Pars plana - columnar

• Function - secrete aqueous humor, blood aqueous barrier, attachment of lens zonules

Label pars plana

1. Medial rectus

2. Sclera

3. Supraciliaris

4. Ciliary muscle

5. Stroma

6. Pigment layer

7. Epithelium

Where is the medial rectus muscle inserted

Inserted into the sclera

Inserted around the pars plana

Label pars plicata muscle fibres

1. Meridional/longitudial fibres

2. Radial/oblique fibres

3. Circular/sphincteric fibres

Describe meridional/longitudinal ciliary muscle fibres

Most anterior

Goes to edge of pars plana

Long and thin

Describe radial/oblique ciliary muscle fibres

In the middle (between meridional and circular)

Run from centre to outside of ciliary body

Describe circular/sphincteric ciliary muscle fibres

Internal/posterior

Ring shaped

What do conjunctival capillary loops supply

The limbus

Label the blood vessels of the anterior eye

1. Conjunctival capillary loops

2. Conjunctival plexus

3. Episcleral plexus

4. Anterior ciliary artery

5. Anterior ciliary vein

6. Long posterior ciliary artery

What are ciliary processes and their function

Lumpy bits of the pars plicata

Ciliary processes attach to zonules

Have a rich vascular blood supply

Produce aqueous

Label the ciliary process

1. Stroma

2. Pigmented epithelium

3. Non pigmented epithelium

Is the non pigmented epithelium outer or inner

Inner - in contact with vitreous and closer to middle/inner of the eye

However it is on the outside of the ciliary process

Unpigmented epithelium function

Produce aqueous

It comes out of the pores in between unpigmented epithelium

Why does the stroma of ciliary processes need a good blood supply

Aquous is produced by unpigmented epithelium

How is aqueous humor produced

From blood in the capillaries of the ciliary processes and trasported to anterior chamber via ciliary epithelium

Pathway of aqueous humor

Formed in ciliary body by ciliary processes by unpigmented epithelium

Moves around the lens and behind the iris to the front of the lens

Flows through the pupil,

Out the anterior chamber through trabecular meshwork into shlemms canal and then to episcleral vessels (anterior angle)

What does pigmented epithelium turn into anteriorly

Anteiror iris epithelium

What does pigmented epithelium turn into posteriorly

Retinal pigment epithelium

What attaches the pigment epithelium to the stroma

Basement membrane (acts as a barrier)

What does non pigmented epithelium turn into anteriorly

Posterior iris epithelium

What does non pigmented epithelium turn into posteriorly

Ora serrata and becomes neural retina

What is aqueous humor and where is it mainly found

A clear fluid found in the anterior and posterior chambers of the eye

What is the rate that aqueous humor is produced

2.75 (+/- 0.63) microlitres per min

Functions of aqueous humor

Provide nutrion to cornea and lens (as theyre avascular)

Removes excretory products from cornea and lens (eg urea,co2)

Contribues to the maintenance of the intraocular pressure of the eye

Which mechanisms is aqueous produced by and describe them

What % of phospholipid bilayer do lipids, protiens and carbohydrates account for

Lipid - 42%

Protien - 55%

Carbohydrates - 3%

Which mechanism is most important in the production of aqueous humor

Osmosis

Role of active transport in the production of aqueous humor

Sodium potassium pump

Flow of Na+, Cl-, HCO3- from unpigmented epithelial cells

Hith concentration of ions causes osmosis of water into intercellular space

What does IOP rely on

The balance between

1. Secretion of aqueous humour from ciliary body

2. Outflow resistance in the trabecular meshwork

(Production and drainage)

Healthy range of IOP

11-21 mmHg

Decreased production of aqueous risks

Low IOP

retinal detachment /Oedema risk

Increased production of aqueous risk

Increased IOP

Glaucoma risk

Normal productiom but less outflow (more resistance to outflow) risks

High IOP

Risk of glaucoma