Retinal Disorders Flashcards
What kind of tests can we do to inspect the retina?
- Direct Ophthalmoscope
- Optical Coherence Tomography
- Fundus Fluorescein Angiography (FFA)
- Electrical Physiology including Electroretinogram (ERG), Electroculogram (EOG) and Visually Evoked Potentials (VEP)
What is Optical Coherence Tomography?
A cross sectional scan of the Fovea Centralis (Macula)
How does a Fundus Fluorescein Angiography work?
Fluorescein dye injected
- > Binds to blood proteins
- > Blue light shone in and excites the fluorescein
- > Light returns and the yellow-green light is isolated with a filter
- > Yellow-green light shows shines on a film
- > Fluorescein filled vessels appear white
This will help you spot any blockages or bleeds from an optical artery
What are the important layers of the retina for us measly 2nd yrs?
Layers 1,2 & 9
1 - Retinal Pigment Layer
2 - Layer of rods and cones
9 = Inner cell fiber layer
What is electrical physiology?
Series of investigations recording electrical signals from the eye, optic nerve or brain in response to visual sitmuli
Includes:
- Electroretinogram (ERG)
- Electrooculogram (EOG)
- Visually Evoked Potentials (VEP)
What does an electroretinogram test?
Action Potentials in the retina in order to measure retinal function
An A wave ERG tests photoreceptors
A B wave ERG tests Muller’s Cells (Retinal Glial cells)
What does an Electrooculogram test?
Function of retinal pigment epithelium and photoreceptors (Layers 9 & 8).
It measures the Resting Potential in both layers and forms a ratio called the Arden Ratio (1.85 is normal)
What does a Visually Evoked Potentials (VEP) Test measure?
They record optic nerve function by measurin electical activity in the visual cortex in response stimuli. (You know cos if optic nerve isnt working the visual cortex wont be active)
What are the pathological signs on a VEP test?
A reduced amplitude in the signals means theres a reduced cell number. Most often due to Ischaemic or Traumatic Optic Neuropathy.
Latency in the signal means the cell function is reduced. Most often due to Optic Neuritis causing demyelination.
List some retinal disorders
- Central Retinal Vein Occlusion
- Central Retinal Artery Occlusion
- Ischaemic Optic Neuropathy
- Optic Neuritis
- Retinal Detachment
- Age Related Macular Degeneration
- Diabetic Retinopathy
- Hypertensive Retinopathy
- Inherited Retinal Dystrophies
- Drug Induced Retinopathy
What retinal disorders cause a gradual visual loss and which a sudden visual loss?
Gradual:
- Age-related Macular Degeneration
- Diabetic Retinopathy
- Inherited Retinal Dystrophies
- Drug Induced Retinopathy
Sudden:
- Retinal Detachment
- Optic Neuritis
- Ischaemic Optic Neuropathy
- Central Retinal Artery or Vein Occlusion
What causes Central Retinal Vein or arterial occlusions?
CRVO:
- Hypertension
- Glaucoma
- Hyperviscosity
- Inflammation
CRAO:
- Emboli
- Inflammation
How does the retina appear on Central Retinal Vein/Artery Occlusions?
CRVO: - The retina is darker - Tortuous dilated veins - Macular & Optic Disc Oedema All because of the back up of blood
CRAO:
- Pale
- Conspicuously lacking blood
What are the types of Ischaemic Optic Neuropathy?
Arteritic (AION) - Usually caused by giant cell arteritis
Non-Arteritic (NAION) - Unknown cause
What is Giant cell arteritis, its symptoms and tests?
The most common form of vasculitis.
- Headache
- Scalp Tenderness
- Jaw Claudication
- Neck Pain
- Nausea/Anorexia
- Visual Loss/Diplopia
Test for inflammatory markers & a Temporal Artery Biopsy
