Macular degeneration Flashcards
What is the most common cause of blindness in the UK?
Macular degeneration
What are 2 functions of the macular?
- Providing central vision
- Providing most of our colour vision
What is the diameter of the macular?
5mm
What are the 4 layers of the macular from top to bottom?
- Photoreceptors
- retinal pigment epithelium
- Bruch’s membrane
- Choroid membrane
What does the choroid layer of the retina contain?
blood vessels that supply the retina and macular
Describe the general pathophysiology of macular degeneration: (2)
- with age, there is degeneration of photoreceptors and atrophy of the retinal pigment epithelial layer
- Drusen deposits form, affecting vision
What are drusen deposits?
yellow deposits of protein and lipids found between the retinal pigment membrane and Bruch’s membrane
What are the two types of macular degeneration?
- Wet (neovascular)
- dry (non-neovascular)
What is wet macular degeneration?
where new vessels develop from the choroid layer and grow into the retina and can leak fluid or blood, causing oedema and faster vision loss
What growth factor is largely responsible for the neovascularisation seen in wet macular degeneration?
VEGF
What % of macular degeneration cases are wet?
10%
What is dry macular degeneration?
where no new vessels form, only degeneration of photoreceptors and atrophy of the retinal pigment epithelium layer
Give 6 risk factors for macular degeneration:
- Increasing age
- Obesity
- Smoking
- CVS such as hypertension
- poor diet (low vitamins and high fat)
- Family history
True or false: macular degeneration typically has a unilateral presentation
True
What are 4 presentations associated with macular degeneration?
- gradual loss of central vision
- reduced visual acuity
- Metamorphosia
- gradually worsening ability to read small text
What is metamorphosia?
where straight lines appear crooked or wavy
What presenting complaint is most commonly associated with macular degeneration?
gradually worsening ability to read small text
Which tends to present more actuely, wet or dry macular degeneration?
wet (it can progress to complete vision loss within 2-3 years)
Give 4 examinations that may be used to investigate macular degeneration:
- Snellen chart (for visual acuity)
- Scotoma assessment (visual field)
- Fundoscopy may show yellow drusen
- Amsler grid test
What is the Amsler grid test for?
metamorphosia
What 2 types of imaging is used to view the retina when investigating macular degeneration?
- optical coherence tomography
- Fluorescein angiography
What is optical coherence tomography?
imaging that allows us to view the layers of the retina and is the primary imaging for diagnosing macular degeneration
What is fluorescein agiography?
imaging the retina with a fluorescein dye that shows any oedema or neovascularisation associated with wet macular degeneration
Give 3 lifestyle changes that can manage risks for those with dry macular degeneration.
- Avoiding smoking
- controlling BP
- Vitamin supplementation
What class of medications are used to manage wet macular degeneration?
anti-VEGF medications (stop the growth of new blood vessels under the retina)
Name 3 anti-VEGF drugs used to treat wet macular degeneration?
- Ranibizumab
- aflibercept
- Bevacizumab
How are anti-VEGF drugs administered into the eye in wet macular degeneration?
injected directly into the vitreous chamber once a month
