Age Related Macular Degeneration

Question 1

What is the definition of sightlessness?

Answer 1

Having less than 1/10 of normal vision in the more efficient eye when refractive problems are fully corrected

Question 2

What develops in retinopathy?

Answer 2

Microaneurysms
Neovascularisation
Heamorrhage
Retinal opacities

Question 3

How do micro-aneurysms appear?

Answer 3

Outpouring of the retinal vasculature that appear as minute, unchanging red dots associated with blood vessels

Question 4

How do micro-aneurysms occlude vision?

Answer 4

Leak plasma, resulting in localised oedema that gives the retina a hazy appearance
They also bleed - contributing to oedema
Affected vision if they encroach on the macula and cause degeneration before they are absorbed

Question 5

How does neovascularisation occur?

Answer 5

Formation of new blood vessels from the choriocapillaries, entering between the pigment and sensory layer, or from the retinal veins, extending between the sensory retina and vitreous cavity and sometimes into the vitreous body
- growth factors, signalling systems and VEGF involved

Question 6

How can neovascularisation causes problems with sight?

Answer 6

The vessel are fragile, lead protein and are likely to bleed

- blurred vision if covers the macular and can cause degeneration

Question 7

What are opacities?

Answer 7

Loss of retinal transparency due to haemorrhages, exudates, cotton wool sports, oedema and tissue proliferation
- exudate result from inflammatory processes

Question 8

How do exudate damage vision?

Answer 8

Destroy the underlying retinal pigment and choroid layer

Question 9

What are cotton wool patches?

Answer 9

Retinal opacities with hazy irregular outlines
These occur in the nerve fibre layer and contain cell organelles
Associated with
- retinal trauma
- severe anaemia
- papillodema
- diabetic retinopathy

Question 10

What are the investigations that can be done to diagnose age related macular degeneration?

Answer 10

Funds fluorescein angiogram
- IV fluorescein injection
- fluorescein binds to albumin which remains in normal capillaries
- use blue and yellow filter to see details of retinal circulation
Optical coherence tomography
- low power laser interferometry
- generates detailed cross-section image of retina

Question 11

Name and describe the two types of AMD.

Answer 11

Exudative 
- new blood vessel formation under retina/above choroid 
- rapid
- metamorphopsia 
Atrophic 
- atrophy of outer retina 
- slow
- blurring

Question 12

How does AMD cause blindness?

Answer 12

Blood vessels and scar tissue grow under the retina
Leaking vessels cause retinal oedema
This blocks transport of oxygen and nutrients from the choroid to the avascular macular
Eventual scarring causes destruction of photoreceptors

Question 13

What are the risk factors for AMD?

Answer 13

Smoking
Age (over 70)
Diet - high doses of vitamin A, C and zinc may be protective 
Family history
Genetics

Question 14

What’s the most common genetic cause of AMD?

Answer 14

Polymorphism sin complement factor H gene

• regulates inflammation and prevents complement mediated attach on own cells
• inflammation is significant in AMD

Question 15

What are other genes that are thought to cause AMD?

Answer 15

Complement genes - CFB, CF1, C2 and C3
Lipids - genes for LDL and HDL
ECM - collagen and matrix metalloproteinase

Question 16

What is thought to start the process of AMD?

Answer 16

Photoreceptors continue to produce photosensitive pigment throughout life
The ends of photoreceptor cells decay and are removed by retinal pigment epithelium constantly
- in some cases the end products accumulate causing drusen
- increases AMD risk

Question 17

What is the best treatment for AMD?

Answer 17

Monoclonal antibodies that inhibit VEGF - to prevent neovascularisation

Question 18

What are the licensed and unlicensed treatments for AMD?

Answer 18

Ranibizumab - licensed (more expensive)

Bevacizumab - unlicensed (less expensive)

Question 19

How is ranibizumab administered?

Answer 19

Intravitreal injection by opthalmologists in a sterile room

Question 20

How often is ranibizumab administered?

Answer 20

Once a month for three months

Question 21

How many people on ranibizumab improved?

Answer 21

40% improved by 15 or more letters on a visual acuity test

Question 22

What are the differences between ranibizumab and bevacizumab?

Answer 22

Injections given as required, not every month
Yearly cost of R=£9656 while B=£1509
Same improvements

Question 23

What are the economic problems or blindness?

Answer 23

Unable to work - loss of employment and income
Requires increased care - more likely to be put in a nursing home
Finance - bank statements and bills

Question 24

What are the problems people with independence that blind people have?

Answer 24

Health risks - falls and fractures
Domestic - cooking, eating, dressing and telephone
Shopping
Navigation - safety

Question 25

What are the problems with communication people with blindness have?

Answer 25

Hearing impairment
Non-verbal communication
Social interactions
TV, film and media

Question 26

What are the psychological problems people with blindness have?

Answer 26

Depression
Anxiety
Increased isolation

Question 27

What is visual acuity?

Answer 27

Recorded as: the distance chart is read/distance at which it should be read

Question 28

What measures must be made when checking visual acuity?

Answer 28

Check if the patients needs distance glasses - get them to wear them
6 meters from the chart
One eye at a time
If vision is imperfect - use a pinhol

Question 29

What extra test should be done is the recorded vision is less than 6/60?

Answer 29

Count finger
Hand motions
Light perception