CVL: Macular degeneration

Question 1

What is macular degeneration?

Answer 1

• Degenerative disease of the macular
• Results primarily in loss of central vision

Question 2

Pathogenesis of macular degeneration

Answer 2

Progressive damage to the RPE and Bruch’s membrane leading to the formation of drusen and new vessel formation known as the choroidal neo-vascularization (CNV)

Question 3

Types of ARMD

Answer 3

1. Dry (non-exudative, non-neovascular)
   - Gradual, progressive central vision loss
   - Drusen formation in the macular
   - Macular RPE atrophy (RPE degenerates and atrophy -> coalescence of depigmented RPE will form clumps of focal hypopigmentation or hyperpigmentation)
2. Wet (exudative, neovascular)
   - Rapid, severe sudden central vision loss
   - Visual loss may manifest as mild metamorphopsia due to distortion in photoreceptor layer from oedema and bleeding

Question 4

For understanding

Answer 4

• Bruch membrane is innermost layer of choroid
• One layer above bruch membrane is layer of RPE cells
• Bruch membrane prevents nutrition from percolating up from the choroid to the retina, and blocks photoreceptor waste products from draining down into the choroidal bed

Question 5

What happens in wet ARMD?

Answer 5

Choroid neovascularisation:
A break occurs in Bruchs membrane, choroid vessels can grow up out of the deep choroidal circulation directly up into the retina (macula)! CNVM is asymptomatic but can be dangerous, as the neovascularization can bleed, create edema, and rapidly destroy vision.

Question 6

What modality can be used to assess choroid neovascularisation?

Answer 6

Fluorescein angiography

Question 7

Risk factors of ARMD

Answer 7

Age!!*
Smoking*
Female
Hereditary
HTN
HLD
Obesity

Question 8

Clinical presentation of ARMD

Answer 8

DRY (which is majority of cases)
- Gradual onset, progressive
- Initially asymptomatic
- Decreased colour sensitivity (colours appear duller)
- Difficulty adjusting from bright to dim light

Progression to wet ARMD:
- Distorted or missing central vision (Central scotoma)
- Early detection with Amsler chart: Metamorphopsia (Lines will appear wavy and distorted, some may be missing)
- Peripheral vision intact

Question 9

Signs of ARMD seen (dry/wet)

Answer 9

Dry
- Bright yellow drusen spots
- Focal/ Widespread geographic atrophy (develops over years)

Wet
- Growth of abnormal vessels in sub-retinal space
- Greyish green discolouration suggestive of choroidal neovascularization
- Subretinal haemorrhage

Question 10

Investigations to send for ARMD

Answer 10

• Fluorescein angiogram
• Optical coherence tomography
• Fasting Lipids/ BP/ DM/ BMI

Question 11

Management of ARMD

Answer 11

Manage with multi-disciplinary team involving Family Physician/ IM physician with an important aspect being to control HLD/ HTN

Patient education
- Monitor regularly with an Amsler grid for metamorphopsia
- Early detection is the key in preventing severe visual loss

Dry ARMD
- Smoking cessation
- Antioxidant Vitamins and Zinc

Wet ARMD
(add on)
- Intravitreal anti-VEGF injections (injected into vitreous cavity to block development of new vessels and leakage from abnormal vessels)
- Photodynamic Therapy
- Thermal Laser Photocoagulation

Advanced RMD
- Low vision aids
- Macular surgery

Question 12

Hallmark finding of RMD

Answer 12

Presence of drusen in macula

Question 13

Early sign of ARMD

Answer 13

Drusen at macular (patient will be asymptomatic)

Question 14

Difference between AREDS 1 and 2

Answer 14

AREDS 1: contains beta carotene (vitamin A)
- increases risk of lung cancer in smokers

Question 15

Early sign of WET ARMD

Answer 15

Metamorphopsia (straight lines appear wavy or distorted) due to blood vessels leaking beneath the macula
-> progress to central scotomas