Retinal Disorders Flashcards
when examining the fundus which vessels are lighter veins or arteries?
arteries (veins are darker)
what does biometry calculate?
lens power
in a fluorescein angiography what part of the eye should be impermeable to fluorescein?
> inner blood retinal barrier (retinal capillaries)
> outer blood retinal barrier (zonula occludens)
what are choriocapillaris permeable to in a fluorescein angiography?
free fluorescein (unbound to serum proteins)
describe the process of a fluorescein angiography
> fluorescein in given to the patient
white light from the camera flash id passed through a blue excitation filter
this blue light excites the fluorescein the blood vessels.
when the picture is being taken the filter is changed to green
green and blue light then exits the eye, only green light enters the camera
what could hypofluoresence in a fluorescein angiography indicate?
blockage and no filling
name some investigations for retinal disorders
> fluorescein angiography
optical coherence tomography
electrophysiological tests
what is optical coherence tomography?
a non-invasive imaging technique that takes a cross sectional image of the retina showing the distinct layers
what are electrophysiology tests?
a series of investigations recording electrical signals from the eye, optic nerve and brain in response to visual stimuli
describe an electroretinogram (ERG)
this measures retinal function by recording action potentials within the retina:
> a wave from photoreceptors
> b wave from mullers cells
describe an electro-oculogram
> measures function of RPE and photoreceptors
measures resting potential difference between RPE and photoreceptors
-maximum potential difference in light adapted eye
- maximum potential difference in dark adapted eye
name the ratio measured in electro-oculogram EOG
arden ratio
describe visually evoked potential VEP investigations
> records optic nerve function
> measures electrical activity in the visual cortex in response to wither a flashing light or checker board pattern
what would a reduced amplitude in visually evoked potentials imply?
> reduced cell number
> ischaemic/traumatic neuropathy
what would latency in visually evoked potentials imply?
> reduced cell function
> optic neuritis
name some common causes of central retinal vein occlusion
> hypertension
glaucoma
hyperviscosity
inflammation
name some conditions resulting in a sudden painless loss of vision
> central retinal vein occlusion > central retinal artery occlusion > ischaemic optic neuropathy > stroke > vitreous haemorrhage > retinal detachment
what are some common causes of central retinal artery occlusion?
> emboli
> inflammation
describe the appearance of the fundus in central retinal artery occlusion
it is very pale with a red spot in the central area
name two types of ischaemic optic neuropathy
> arteritic
> non-arteritic
what is happening in ischaemic optic neuropathy?
the optic nerve is not receiving any blood supply and is becoming oedemic
describe the symptoms seen in giant cell arteritis
> headache > scalp tenderness > jaw claudication > neck pain > nausea > loss of vision
what is raised in giant cell arteritis?
inflammatory markers
what symptoms and signs are seen in optic neuritis?
> pain on eye movement > reduced vision > red desaturation > central scotoma > relative afferent pupil defect > swollen optic disc
name some conditions that could cause a gradual painless loss of vision
> cataracts > refractive error > age related macular degeneration > open angle glaucoma > diabetic retinopathy > hypertensive retinopathy > inherited retinal dystrophies > drug induced retinopathy
describe the vision loss in macular degeneration
there is progressive loss of central vision (and ability to see colour can also decrease0
what are the risk factors associated with age related macular degeneration?
> age
smoking
poor diet
what is seen on the retina in diabetic retinopathy?
> capillary non-perfusion > micro aneurysm > capillary fallout > cotton wool spots > exudates
what can happen in advanced diabetic retinopathy?
membranes can develop and the retina is pulled out
what is the treatment option for diabetic retinopathy?
laser treatment saving the posterior fold
what are retinal dystrophies?
series of inherited conditions affecting photoreceptor function leading to progressive loss of vision
name some photoreceptor dystrophies
> retinitis pignemtosa
cone dystrophy
lebers congenital amaurosis
name some RPE-dystrophies
> best’s vitelliform macular dystrophy
stargardt macular dystrophy
sorsby macular dystrophy
north Carolina macular dystrophy
name some choroidal dystrophies
> choroideraemia
> gyrate atrophy
name some vitreoretinal dystrophies
> stickler syndrome
> congenital retinoschisis
is photopic ERG reduced or raised in cone dystrophy?
reduced
is cone dystrophy dominant or x linked recessive?
both! (IDK how or why but that s what it says)
is best’s vitelliform macular dystrophy dominant or recessive?
dominant
is stargardt macular dystrophy recessive or dominant?
recessive
is sorsby macular dystrophy dominant or recessive?
dominant
is north Carolina macular dystrophy dominant or recessive?
dominant
describe the inheritance of choroideraemia
it is x linked recessive
describe the pathophysiology of choroideraemia
there is dystrophy of the choroid so there is not much blood supply to the retina leaving it quite pale
is gyrate atrophy dominant or recessive?
recessive
what drugs can induce retinopathy?
> antimalarials
phenothiazines
tamoxifen
what accumulates in the back of the eye is central serous retinopathy?
fluid
name some acquired maculopathies associated with age
> idiopathic macular hole
> epiretinal membrane
for what is gene therapy used?
choroideraemia
