Retinal Disorders Flashcards
(48 cards)
What examinations of the eyes can be carried out?
- Direct ophthalmoscope
- Indirect ophthalmoscope
- Fundoscopy
- Biometry
- Perimetry
- Optical coherence tomography
- Fluorescein angiography
What is the inner blood-retinal barrier (retinal capillaries) impermeable to?
Fluorescein
What is the outer blood-retinal barrier (zonula occludens) impermeable to?
Fluorescein
What is the choriocapillaries permeable to?
Free fluorescein
In fluorescein angiography how does the fluorescein bind?
- 85% bound to serum proteins
- 15% unbound free fluorescein
What type of light excites fluorescein in the blood vessels?
Blue light
What type of light emerges from the eye during fluorescein angiography?
Yellow-green and blue light
What type of cells are more prevalent in the fovea?
Cone cells
What is the blind spot?
The area where there is no photoreceptors
Electrophysiology
A series of investigations recording electrical signals from the eye, optic nerve and brain in response to visual stimuli
Electroretinogram
-Measures retinal function
Records action potentials within the retina (a waves from photoreceptors and b waves from Muller’s cells)
Electro-oculogram
- Measures function of RPE and photoreceptors
- Measures resting potential difference between the RPE and photoreceptors
- Maximum potential difference in light adapted eye
- Minimum potential difference in dark adapted eye
- Arden ration 1.85
Visually Evoked Potentials
- Records optic nerve function
- Measures electrical activity in the visual cortex in response to either a flashing light or a checker board pattern
What can visually evoked potentials reveal?
Reduced amplitude -Reduced cell number -Ischaemic/traumatic optic neuropathy Latency -Reduced cell function -Optic neuritis
What investigations should be carried out to diagnose a retinal pathology?
- Visual acuity, visual fields, colour vision, RAPD
- Fundoscopy
- Fluorescein angiography
- Optical coherence tomography
- Electrophysiology
What can cause sudden painless loss of vision?
- Central retinal vein occlusion
- Central retinal artery occlusion
- Ischaemic optic neuropathy
- Stroke
- Vitreous haemorrhage
- Retinal detachment
- Sudden discovery of pre-existing unilateral LoV
What are the common causes of central retinal vein occlusion?
Hypertension
- Glaucoma
- Hyper viscosity
- Inflammation
What are the common causes of central retinal artery occlusion?
- Emboli (carotids/heart)
- Inflammation
What are the 2 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
What investigative result may indicate giant cell arteritis?
- Raised inflammatory markers
- Positive temporal artery biopsy
What are the signs and symptoms of optic neuritis?
- Pain on eye movements
- Reduced vision
- Red desaturation
- Central scotoma
- Relative afferent pupil defect
- Swollen optic disc
What can cause gradual painless loss of vision?
- Cataract
- Refractive error
- Age-related macular degeneration
- Open-angle glaucoma
- Diabetic retinopathy
- Hypertensive dystrophies
- Inherited retinal dystrophies
- Drug-induced retinopathy
What does age-related macular degeneration present with?
Progressive loss of central vision
