Retina Flashcards
What is the volume of the vitreous?
4-4.4ml
What three materials is the vitreous composed of?
water
hyaluronic acid
type 2 collagen
From which embryological structure is the retina derived?
diencephalon
How many layers make up the retina?
10
How many rods are there in the neurosensory retina?
120 million
Where is the highest density of rods in the retina?
mid-peripheral retina
What pigment is found in the rods?
rhodopsin
How many rods can one bipolar cell receive signals from?
50-100
What is the function of the rods?
Night and peripheral vision
How many cones are there in the neurosensory retina?
6 million
Where is the highest density of cones found?
macula and fovea
What pigment is found in the cones?
iodopsin
How many cones does one bipolar cell receive signals from?
1
What is the function of the cones?
central and colour vision
What are the three functions of the retinal pigment epithelium?
absorbs light, preventing scattering of light in the eye
blood-retinal barrier provides selectively permeable membrane to deliver nutrients to the photoreceptors and maintain homeostasis
transport of vitamins and metabolites
where is there macula located compared to the optic disc?
temporally
how does blood reach the fovea?
diffusion from choriocapillaries
what name is given to retinal glial cells?
Muller cells
Which artery supplies the outer 1/3 of the retina, including the photoreceptors and RPE?
short posterior ciliary artery
Which artery supplies the inner 2/3 of the retina?
central retinal artery
What is the pathophysiology of diabetic retinopathy?
hyperglycaemia caused increased retinal blood flow and damage to the endothelium and pericytes
How are hard exudates formed in diabetic retinopathy?
lipoproteins deposited in outer plexiform layer
Why are flame haemorrhages seen in diabetic retinopathy?
pericyte damage predisposes to microaneurysm and rupture of the capillary walls
What is the effect does decreased HbA1c by 1 have on progression of diabetic retinopathy?
decreases rate of progression by 37%
In T1DM, what is the risk of developing diabetic retinopathy at:
A 10 years
B 30 years?
A 50%
B 90%
At least one microaneurysm, intraretinal haemorrhages, exudates or cotton wool spots?
mild non-proliferative DR
intraretinal haemorrhages in 1-2 quadrants, venous beading in one quadrant or mild intraretinal microvascular abnormality
moderate non-proliferative DR
intraretinal haemorrhages in 4 quadrants, venous beading in >2 quadrants and moderate intraretinal microvascular abnormality in >1 quadrant.
severe non-proliferative DR
4-2-1 rule
what features make proliferative diabetic retinopathy “high risk”?
NVD >1/3 of dic
NVD plus vitreous haemorrhage
NVE >1/2 disc area plus vitreous haemorrhage
What is a sign of advanced proliferative diabetic retinopathy?
tractional retinal detachment
What is the management for non-high risk PDR?
review in 2 months
What is the management of high risk PDR?
panretinal photocoagulation within 1 week
What is the management of diabetic maculopathy?
intravitreal vegf
Is hypertension more closely related to CRVO or BRVO?
BRVO
where are dot/blot haemorrhages most commonly seen in BRVO?
superotemporal quadrant
does RVO cause a painful or painless loss of vision?
painless
What is the management of non-ischaemic RVO?
anti vegf if VA >6/96 and OCT shows MO
What is the management of ischaemic RVO?
urgent panretinal photocoagulation +/- cyclodiode laser of neovascularisation
Sudden painless loss of vision, marked RAPD. Fundoscopy shows pale retina, cherry red spot, arteriolar attenuation.
CRAO
What conditions are associated with CRAO?
atherosclerosis
GCA
What investigations should be carried out in suspected CRAO?
ESR, plasma viscosity, carotid doppler
Altitudinal visual field loss. Wedge shaped pallor, arteriolar attenuation
BRAO
Which anatomical variation can spare some of the visual field loss associated with RAO?
cilioretinal artery
What conditions are associated with cystoid macular oedema?
diabetic macular oedema CRVO/BRVO ARMD anterior and post. uveitis retinitis pigmentosa Irvine gass syndrome
Which medications can cause cystoid macular oedema?
nicotinic acid
prostaglandin analogues
epinephrine
Patient with abnormal Hb. Salmon patches (intraretinal haemorrhages) and black sunbursts (RPE hyperplasia)?
non-proliferative sickle cell retinopathy
What system is used in classification of proliferative sickle cell retinopathy?
Goldberg classification
What is an end-stage complication of proliferative sickle cell retinopathy?
retinal detachment
What is the leading cause of blindness in developed countries?
ARMD
Older white female smoker. Central vision loss and metamorphosia. Soft drusen on fundoscopy.
dry ARMD
By which mechanism does cell death occur in ARMD?
apoptosis
Mutation in which genes can increase risk of developing ARMD?
CFH and ARMS2
What unilateral variant of wet ARMD is seen in middle aged, Asian populations?
polypoidal choroidal vasculopathy
What is the management of dry ARMD?
smoking cessation advice vitamin supplementation (C, E, lutein, zeaxanthin and zinc)
What is the management of wet ARMD?
anti-vegf
amsler grid
OCT
Young male patient, type A personality. Unilateral decreased VA, metamorphosia, central scotoma. Slow recovery from bright lights. Associated with corticosteroid use. OCT shows triangle shaped subretinal fluid collection with neurosensory retinal detachment
central serous chorioretinopathy
What is the management of central serous chorioretinopathy?
photodynamic therapy
Young indian male. Recurrent vitreous haemorrhage. Associated with TB.
Eales disease
What is the management of Eales disease?
corticosteroids
What is the most common melanoma of the uveal tract? Where does it most commonly metastasise to?
choroidal melanoma
liver
Unilateral decreased VA and field loss. Fundoscopy shows pigmented, raised, subreinal mass with collar stud appearance.
choroidal melanoma
Angioid streak occurs as a result of breaks in which layer of the retina?
Bruch membrane
Bilateral symmetrical peripapillary atrophy with multiple irregular streaks radiating from the optic disc (angioid streak). Plucked chicken appearance of skin in neck, inguinal folds and antecubital fossa
Pseudoxanthoma elasticum
What is the inheritance pattern of:
A ocular albinism?
B oculocutaneous albinism?
A X linked
B AR
Why is VA decreased in albinism?
foveal hypoplasia
How does the optic chiasm differ from normal in patients with albinism?
more crossed fibres
Patient with very pale skin and hair, nystagmus, strabismus, pink eyes.
albinism
Condition causing mulberry lesions (creamy white, well circumscribed glial tumours), associated with TB, NF and retinitis pigmentosa.
Retinal astrocytic hamartomas
AD condition. Retinal capillary haemangioma with tortuous feeder vessels, pheochromocytoma, hemangioblastoma, renal cell carcinoma
Von-Hippel Lindau
Patient presents temp and new murmur. Fundoscopy shows pink fleshy lesions with white patches. What is this sign called?
Roth spots (infective endocarditis)
What inherited systemic condition can cause retinal hamartomas? Patient has strange growths under their nails.
Tuberous sclerosis
IVDU, appears emaciated, systemically unwell. Fundoscopy has pizza pie appearance.
CMV retinitis
Patient 34 weeks pregnant. Complaining of headache and flashes in peripheral vision. Fundoscopy shows macular star, cotton wool spots and disc swelling bilaterally.
Pre-eclampsia