Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Ocular Anatomy and Physiology > Week 10: Aqueous, Vitreous Humour & Vitreo-Retinal Attachments > Flashcards

Week 10: Aqueous, Vitreous Humour & Vitreo-Retinal Attachments Flashcards

1
Q

Describe the anterior segment structure

A
  1. Anterior Chamber
    - Filled with aqueous humour (0.2 mL)
    - Measures 3 mm at greatest depth centrally
    - Anterior limit: cornea & sclera
    - Posterior limit: iris & lens
  2. Posterior Chamber
    - Filled with aqueous humour (0.06 mL)
    - Narrow area
    - Anterior limit: iris
    - Posterior limit: lens & zonules
    - Peripheral limit: ciliary processes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the angle structures of the anterior chamber from anterior to posterior.

A
  1. Schwalbe’s Line
  2. Trabecular Meshwork (non-pigmented)
  3. Trabecular Meshwork (pigmented)
  4. Scleral Spur
  5. Ciliary Body Band
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe Schwalbe’s Line

A
  • Most anterior structure in the angle
  • Looks like an ‘opaque’ line
  • Termination of Descemet’s membrane
  • Pigment visible anterior to Schwalbe’s line is called a sampaolesis line
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe Trabecular Meshwork in general

A
  • Forms aqueous outflow pathway with the scleral spur, ciliary muscle and Schlemm’s canal
  • Apex of the outflow pathway is at Schwalbe’s line and base is at the scleral spur.
  • Inner wall of the TM faces the anterior chamber
  • Outer wall of the TM is attached to the inner wall of Schlemm’s canal
  • Involved with homeostasis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe Trabecular Meshwork non-pigmented

A
  • Anterior portion is usually less pigmented

- The non-filtering portion of the meshwork

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe Trabecular Meshwork pigmented

A
  • As fluid flows through here, posterior TM tends to collect pigment with age as it is shed from other structures e.g. the iris
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the Trabecular meshwork 3 components histologically from posterior to anterior

A
  1. Uveal Meshwork (inner)
  2. Corneo-scleral Meshwork (central)
  3. Juxtacanalicular tissue/Cribriform layer (outer)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the uveal meshwork

A
  • Large pores exist between tissue and lamellae
  • Contributes little resistance to aqueous outflow
  • Thickness highly variable between eyes
  • Cells of the outer layers of TM acts as pre-filters and are aggressively phagocytic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the corneo-scleral meshwork

A
  • Makes up bulk of TM
  • Inner layers arise from ciliary muscle fibre insertions and outer layer arise from scleral spur
  • Cells of outer layers of the TM act as pre-filters and are aggressively phagocytic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the juxtacanalicular tissue/cribriform layer

A
  • Outer portion of trabecular meshwork
  • Outer aspect formed by endothelial cells, lining inner wall of Schlemm’s canal
  • Principle site of aqueous outflow resistance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe scleral spur

A
  • Protrusion of sclera into anterior chamber

- Connects with TM anteriorly and ciliary body band posteriorly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe ciliary body band

A
  • Ciliary face between the peripheral iris and scleral spur

- Can be observed through gonioscopy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe canal of schlemm

A
  • Circular vessel and oval shape in cross-section
  • Lies parallel and continuous with outer aspect of trabecular meshwork
  • Function: venous channel for aqueous drainage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What structures do you observe with wide open grading scale

A
  • Ciliary body band
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What structures do you observe with Grade I

A
  • Schwalbe’s line
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What structures do you observe with Grade II

A
  • Trabecular meshwork
17
Q

What structures do you observe with Grade III

A
  • Scleral spur
18
Q

What structures do you observe when it’s closed

A
  • No structures

- Schwalbe’s line not visible

19
Q

What does the aqueous humour consist of

A
  • Consists of clear liquid

- Contains: electrolytes, glucose, amino acids, ascorbic acid, dissolved gases & waste products

20
Q

Describe what the aqueous humour and its dimensions

A
  • Constantly in motion & entire volume is replaced every 1-2 hours
  • Rate of formation 2 µL/min
  • Volume of Anterior Chamber = 0.2 mL
  • Volume of Posterior Chamber = 0.06 mL
21
Q

What is the function of the aqueous humour?

A
  • Maintains the shape of the globe constant

- Maintains the pressure of the eye and corneal nourishment

22
Q

Describe the aqueous humour production

A
  1. Active Secretion
    - 80% is secreted by non-pigmented layer of ciliary epithelium by metabolic pump independent of IOP
  2. Passive Secretion
    - 20% is produced by diffusion & ultrafiltration dependent upon blood pressure, plasma oncotic pressure and IOP
23
Q

Describe the aqueous humour outflow

A
  • Flows from ciliary processes through posterior chamber
    • Pars plicata
    • Pars plana
  • Through the pupil
  • Flows to anterior chamber where it is drained from the eye
24
Q

Explain the aqueous drainage of: trabecular (conventional pathway)

A
  1. 90% drained through TM into Schlemm’s canal
  2. Aqueous flows from Schlemm’s canal to collecting channels and venous plexi
  3. Exits the eye through the episcleral veins
25
Q

Explain the aqueous drainage of uveoscleral (unconventional pathway)

A
  1. Aqueous passes through ciliary muscle into supraciliary anteriorly and suprachoroidal posteriorly spaces
  2. Drained by venous circulation in the ciliary body, choroid and iris roots
26
Q

Describe the physiology of intraocular pressure and its measurement

A
  • Normal IOP = 15.9 mmHg
  • Physiological IOP differs in patients
  • Fluctuates and elevates in morning and diurnal variation
  • Goldman equation determines IOP in mmHg

IOP is determined by:

  1. Rate of aqueous secretion
  2. Resistance to aqueous outflow
  3. Level of episcleral venous pressure
27
Q

Discuss the blood aqueous barrier

A
  • Restriction of solutes travelling from ocular vasculature to aqueous humour
  • Consists of:
    • Tight junctions of the ciliary processes non-pigmented epithelium
    • Inner wall of Schlemm’s canal
28
Q

What is the break down of the blood aqueous barrier?

A
  1. Disease (i.e. intraocular infections)
  2. Trauma (i.e. blunt trauma, alkali burns, corneal abrasions)
  3. Drug induced
  4. Inflammation (ie. anterior uveitis)
29
Q

Describe the vitreous chamber

A
  • Filled with gel-like vitreous body

- Makes up 80% volume of the eye

30
Q

What are the three zones of the vitreous chamber and describe them briefly?

A
  1. Vitreous Cortex
    - Outer zone
    - Composed of tightly packed collagen fibrils
  2. Intermediate Zone
    - Fine fibres that are unbranched
    - Run anterior to posterior
  3. Cloquet’s canal
    - Located in centre of vitreous body
    - Has an S shape
31
Q

List the vitreous points of attachment

A
  1. Ora serrata
  2. Vitreous base
  3. Anterior hyaloid
  4. Posterior hyaloid
  5. Retrolental ligament
  6. Retrolental space
32
Q

What are the functions of the vitreous body?

A
  • Support function for the retina
  • Filling function to maintain eye shape
  • Diffusion barrier between anterior and posterior segments of the eye
  • Metabolic buffer
33
Q

What is glaucoma and what are some types?

A
  • Pathological loss of retinal ganglion cell axons

Types:

  • Primary Open Angle Glaucoma: no identifiable cause
  • Primary Closed Angle Glaucoma
  • Secondary glaucoma
34
Q

What is posterior vitreous detachment?

A
  • Gel volume decreases and liquid volume increases

- Traction may detach the posterior vitreous from the retina

Ocular Anatomy and Physiology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions