AMD

Question 1

What are the features of dry type macular degeneration?

Answer 1

Gradual reduction of central vision
Difficulties recognising faces and reading
Presence of druse, retinal pigment atrophy
Generally less visually disabling
No form of treatment rot restore vision

Question 2

What are the features of wet type macular degeneration (10%)?

Answer 2

Rapid loss of central vision, may start with distortion of central vision (metamorphosa)
Progresses to central scotoma
Causes profound visual handicap

Question 3

Why does wet type AMD occur?

Answer 3

Result of new vessels growing form the choroid into the macula region of the retina causing retinal elevation
May be associated with retinal haemorrhages and oedema
vessels bleed and leak fluid which subsequently leaks and result in scar formation

Question 4

What is the treatment for AMD?

Answer 4

Largely unsatisfactory
Photocoagulation may help
Emergence of new therapy photodynamic therapy looks promising

Question 5

Why does dry type AMD occur?

Answer 5

Due to atrophy of the photoreceptors in the retinal pigment epithelium- it starts with atrophy of the RPE and inner choroid- leads to death of photoreceptors
Drusens (soft
thickenings of Bruch’s membrane) occur and are responsible for the mentioned changes
This type is responsible for 90% of cases of AMD but only 10-20% of severe visual loss in AMD

Question 6

What are drusens?

Answer 6

focal thickening of Bruch’s membrane which separates the photoreceptors from the choroid and hence their blood supply

Question 7

What are risk factors for drusens?

Answer 7

Age
Smoking
CVD- HTN or hyperlipidaemia
Low antioxidants in the blood

Question 8

What is important for laser treatment?

Answer 8

The location of the choroidal new vessels in relation to the centre of the fovea
Extrafoveal: > 200u from centre
Juxtafoveal: > 1-199u from centre
Subfoveal

Question 9

What occurs in laser photocoagulation?

Answer 9

Non- selective thermal laser which destroys the choroidal neovascular lesions and can also damage the overlying retina
Eligibility is for Extrafoveal or Juxtafoveal lesions, presence of classical CVN and well demarcated lesion boundaries
13-26% of patients of eligible for treatment but leakage persists/recurs in 50%

Question 10

What are the other treatments available for wet type AMD?

Answer 10

Surgery: submacular excision of CNV - didn’t work, and macular rotation – 80% recurrence with high rejection rate
Radiotherapy: less used
Photodynamic Therapy: currently used
Pharmacological agents

Question 11

Which pharmacological agents are used to treat wet type AMD?

Answer 11

Macugen (isoform 165) and Lucentis (all isoforms)- antagonise VEGF
Can’t be used permanently as VEGF is neuroprotective- lasts 4-6 weeks
Triamcinolone (long acting steroid): anti-permeability and anti- inflammatory, only mildly anti-angiogenic
side effects: cataracts and increased IOP
Combination treatment can be used