Age-related Macular Degeneration

Age-related Macular Degeneration (AMD) is the degeneration of the macula that causes progressive deterioration in vision, and it's the most common cause of blindness in the UK. It's classified into Wet (10%) and Dry (90%) - Wet type has a worse prognosis.

Risk factors - Age, Smoking, CVD, FHx

The Macula is made up of 4 key layers (bottom to top):

• Vascular choroid later

• Bruch’s membrane

• Retinal pigment epithelium

• Photoreceptors

In AMD, there is:

• Atrophy of retinal pigment epithelium

• Degeneration of photoreceptors

• Specific to Dry AMD:

  • Drusen - Protein and lipid deposits form in the macula

  • Geographic atrophy - Macular thinning that occurs

• Specific to Wet AMD:

  • Neovascularisation from the choroid layer into the retina - Can leak fluid and cause oedema

    • VEGF is important here, so treatment drugs target it

Presentation

• Gradually worsening central vision loss

  • Wet AMD has a much more rapid progression

• Crooked/wavy appearance to straight lines

• O/E:

  • Dry AMD - Drusen - Yellow deposits of protein and lipids between the retinal pigment epithelium and Bruch’s membrane

  • Wet AMD - Subretinal/intraretinal haemorrhages (newer vessels tend to be weaker and more fragile)

  • Reduced visual acuity

  • Scotoma – Central patch of vision loss (i.e. enlarged blind spot)

Investigations

• Fundoscopy

• Optical coherence tomography (OCP)

• Fluorescein angiography if Wet AMD is suspected

Management

• Lifestyle modifications to slow disease progression e.g. Smoking cessation, BP control

• Anti-VEGF medications e.g. Ranibizumab etc. to slow disease progression