Retinal Disorders Flashcards
Where are cones concentrated in the eye?
The fovea
Where are cones concentrated in the eye?
The periphery
Describe the principle of electrophysiology
A series of investigation recording electrical signals for the eye, optic nerve and brain in response to visual stimuli
What is an electroretinogram?
A test to measure retinal function. It records APS within the retina, measures a-waves and b-waves
Where do the a-waves detected in electroretinogram originate?
Photoreceptors
Where do the b-waves detected in electroretinograms originate
Muller’s cells
What is an electro-oculgram?
It measures the function of RPE and photoreceptors via the resting potential difference between the RPE and photoreceptors
What are visually evoked potentials?
A test to measure optic nerve function - it measures electrical activity int he visual cortex in response to either a flashing light or a checker board pattern
Can can a result of reduced amplitude in visually evoked potentials be indicative of?
Reduced cell number
Ischaemic/traumatic optic neuropathy
What can a result of reduced amplitude in visually evoked potentials be indicative of?
Reduced cell function
Optic neuritis demyelination
Give the common causes of central retinal vein occlusion
Hypertension
Glaucoma
Hyperviscosity
Inflammation
Give the common causes of central retinal artery occlusion
Emboli (carotids/heart)
Inflammation
What are the two types of ischaemic optic neuropathy?
Arteritic (AION)
Non-Arteritic (NAION)
What are the symptoms of Giant Cell Arteritis?
Headache Scalp tenderness Jaw claudication Neck pain Nausea/anorexia Loss of vision
Where are cones concentrated in the eye?
The periphery
Describe the principle of electrophysiology
A series of investigation recording electrical signals for the eye, optic nerve and brain in response to visual stimuli
What is an electroretinogram?
A test to measure retinal function. It records APS within the retina, measures a-waves and b-waves
Where do the a-waves detected in electroretinogram originate?
Photoreceptors
Where do the b-waves detected in electroretinograms originate
Muller’s cells
What is an electro-oculgram?
It measures the function of RPE and photoreceptors via the resting potential difference between the RPE and photoreceptors
What are visually evoked potentials?
A test to measure optic nerve function - it measures electrical activity int he visual cortex in response to either a flashing light or a checker board pattern
Can can a result of reduced amplitude in visually evoked potentials be indicative of?
Reduced cell number
Ischaemic/traumatic optic neuropathy
What can a result of reduced amplitude in visually evoked potentials be indicative of?
Reduced cell function
Optic neuritis demyelination
Give the common causes of central retinal vein occlusion
Hypertension
Glaucoma
Hyperviscosity
Inflammation
Give the common causes of central retinal artery occlusion
Emboli (carotids/heart)
Inflammation
What are the two types of ischaemic optic neuropathy?
Arteritic (AION)
Non-Arteritic (NAION)
What are the symptoms of Giant Cell Arteritis?
Headache Scalp tenderness Jaw claudication Neck pain Nausea/anorexia Loss of vision
Give some symptoms of optic neuritis?
Pain on movement Reduced vision Red desaturation Central scotoma Relative afferent pupil defect Swollen optic disk
What is age-related macular degeneration?
The majority of people affected are over 60, is a progressive loss of central vision. Two types - dry and wet
What are the risk factors for age-related macular degeneration?
Age
Smoking
Poor diet
What is diabetic retinopathy?
Damage to the retina caused by diabetes, occurs in 80% of patients who have had diabetes for over 10 years, leads eventually to blindness
What are the signs of diabetic retinopathy on visualisation?
Cotton wool spots
Visible exudates
Vascular anomalies - venous beading, ischaemia
What are retinal dystrophies?
A series of inherited conditions affecting photoreceptor function leading to progressive loss of vision
What are the two kinds of retinal dystrophies?
Photoreceptor dystrophies - ERG reduced
RPE-dystrophies - EOG reduced
