age related macular degeneration. Flashcards
what are the 2 types of macular degeneration?
dry- 90%
wet- 10%- carries worse prognosis
what is the key finding with macular degeneration?
Drusen are yellow deposits of proteins and lipids that appear between the retinal pigment epithelium and Bruch’s membrane during fundoscopy.
what are the 4 layers of the macular?
- photoreceptors at the top
- retinal epithelium
- bruch’s membrane
- choroid layer-> contains blood vessles
what is the macular responsible for?
The macula is part of the retina at the back of the eye. It is only about 5mm across but is responsible for our central vision, most of our colour vision and the fine detail of what we see.
what is the pathophysiology of wet macular degeneration?
In wet AMD there is the development of new vessels growing from the choroid layer into the retina. These vessels can leak fluid or blood and cause oedema and more rapid loss of vision.
A key chemical that stimulates the development of new vessels is vascular endothelial growth factor (VEGF) and this is the target of medications to treat wet AMD.
There is no specific treatment for dry age-related macular degeneration. Management focuses on lifestyle measure that may slow the progression
what are the risk factors for age related macular degeneration?
Age Smoking White or Chinese ethnic origin Family history Cardiovascular disease
how will patients with macular degeneration present?
Gradual worsening central visual field loss
Reduced visual acuity
Crooked or wavy appearance to straight lines
Wet age-related macular degeneration presents more acutely. It can present with a loss of vision over days and progress to full loss of vision over 2-3 years. It often progresses to bilateral disease.
which are the lifestyle changes which can slow the progression of dry AMD?
Avoid smoking
Control blood pressure
Vitamin supplementation has some evidence in slowing progression
what are the first and second line investigations for wet macular degeneration?
1st=Optical coherence tomography is a technique used to gain a cross-sectional view of the layers of the retina.
2nd=Fluorescein angiography involves giving a fluorescein contrast and photographing the retina to look in detail at the blood supply to the retina.
It is useful to show up any oedema and neovascularisation. It is used second line to diagnose wet AMD if optical coherence tomography does not exclude wet AMD.
what are the initial investigations to do when diagnosing AMD?
Reduced acuity using a Snellen chart
Scotoma (a central patch of vision loss)
Amsler grid test can be used to assess the distortion of straight lines
Fundoscopy. Drusen are the key finding.
what are the medications used to treat wet AMD?
Medications such as ranibizumab, bevacizumab and pegaptanib block VEGF and slow the development of new vessels.
They are injected directly into the vitreous chamber of the eye once a month. They slow and even reverse the progression of the disease.
They typically need to be started within 3 months to be beneficial.
