Disorders of the Retina Flashcards
What does an electroretinogram measure?
Retinal function - records action potentials within the retina: A wave from photoreceptors and B-wave from Muller’s cells
What does an electrooculogram measure?
Function of RPE and photoreceptors
Resting potential difference between the RPE and photoreceptors
What do visually evoked potentials record?
Optic nerve function
What do visually evoked potentials measure?
Electrical activity in visual cortex in response to either a flashing light or a checker board pattern
What is reduced amplituded on visually evoked potentials indicate?
Reduced cell number
Ischaemic/traumatic optic neuropathy
What does latency on visually evoked potentials indicate?
Reduced cell function
Optic neuritis
What are common causes of central retinal vein occlusion?
Hypertension
Glaucoma
Hyperviscosity
Inflammation
What are the common causes of central retinal artery occlusion?
Emboli
Inflammation
What happens in ischaemic optic neuropathy?
Can lose vision, starts with loss of vision in one eye and can then cause loss in both if untreated
How do you tell arteritic and non-arteritic ischaemic optic neuropathy apart?
Blood test for inflammatory markers and raised CRP
What are examples of gradual painless loss of vision?
Cataract Refractive error Age related macular degeneration Open angle glaucoma Diabetic retinopathy Hypersensitive retinopathy Inherited retinal dystrophies Drug induced retinopathy
What are the risk factors for age-related macular degeneration?
Age
Smoking
Poor diet
What are inherited retinal dystrophies?
Series of inherited conditions affecting photoreceptor function leading to progressive loss of vision
What are types of photoreceptor dystrophies?
Retinitis pigmentosa
Cone dystrophy
Leber’s congenital amaurosis
What is cone dystrophy?
Sporadic
Dominant, X linked recessive
Phototopic ERG reduced, scotopic normal
