Retinal Vascular Disease Flashcards
the macula is what
The macula is the central and thickest part of the retina, temporal to the optic disc.
There is a high concentration of cone photoreceptors
The presence of xanthophyll pigment gives the macula a yellow tinge
the fovea is what
The fovea is a small depression in the centre of the macula.
It lies 2 disc diameters temporal to the edge of the optic disc
It can be recognised by a tiny reflection of light from your ophthalmoscope (foveal reflex)
where are the photoreceptors located
The outer retina consists of a layer of sensory cells called photoreceptors
These are of two types, rods and cones
The cones are responsible for colour vision and good visual acuity
The rods are responsible for night vision
retinal pigmented epithelium is what
The RPE is a pigmented layer just below the photoreceptors
It is responsible for all of the metabolic needs of the photoreceptors
what is the choroid
The choroid is a highly pigmented and vascular layer just below the RPE
It provides the nutrition and oxygen needs of the outer retina
It has a very high blood flow
what is the blood retinal barrieer
This is analogous to the blood-brain barrier
Tight intercellular junctions in the retinal blood vessels and the RPE stop leakage of blood contents into the retina
Most retinal vascular disease is associated with damage to this barrier
retinal vascular disease is what
Systemic arterial hypertension
Diabetic retinopathy
Other types of retinal vascular disease include:
Sickle cell retinopathy
Retinopathy of prematurity
retinal haemorrhages are what
Retinal haemorrhages are an important sign of retinal vascular disease
They occur in different layers of the retina and as a consequence have different appearances:
Pre-retinal (also called sub-hyaloid)
Superficial nerve fibre layer (flame)
Intraretinal- dot and blot
Subretinal
what is a pre-retinal haemhorrhage
They lie between the retina and the vitreous gel
They settle to form a horizontal level
They are found in proliferative diabetic retinopathy, subarachnoid haemorrhage and valsalva haemorrhages
what are flame haemhorrhages
they look like tye dye
what are dot and blot haemhorrhages
These haemorrhages lie deeper in the retina
Blot haemorrhages are a sign of retinal ischaemia
They are found in diabetic retinopathy
what are subretinal haemorrhages
These lie under the retina and cause a small retinal detachment and are often circular
They originate from the choroidal blood vessels
They are found in macular degeneration
what is systemic hypertension
The severity of retinopathy depends upon the height of the blood pressure, the speed of onset and the duration.
The features of hypertensive retinopathy are caused by damage to the blood-retinal barrier, leading to leakage from retinal capillaries, and thickening of blood vessel walls.
how is hypertensive retinopathy classfied
Modified Scheie classification
Grade 0 no changes
Grade 1 barely detectable arterial narrowing
Grade 2 arterial narrowing with focal irregularities
Grade 3 grade 2 plus haemorrhages +/- exudates +/- cotton wool spots
Grade 4 grade 3 plus disc swelling (malignant hypertension)
what are common findings in hypertnesive retinopthay
Common findings in chronic elevated BP:
Focal or generalised narrowing of arterioles
Intra-retinal haemorrhages
Branch retinal artery occlusions
Central retinal vein occlusions
Branch retinal vein occlusions
Retinal macroaneurysms
how can systemic hypertension affect the choroidal blood vessels
Systemic hypertension can also affect
the choroidal blood vessels. Particularly
in eclampsia and other causes
of accelerated BP
Signs are:
Elschnig spots (pale spots with pigment)
Siegrist streaks
what are elschnig posing spots
small chorioidal infarcts
what factors dtermine if someone with diabetes will develop retinopathy
There are several factors which determine whether a patient with diabetes will develop retinopathy:
Duration
After 20 years 99% of IDDM and 60% NIDDM will have retinopathy
Control of glycaemia (Hb A1c levels)
Other factors: blood viscosity, elevated lipids
Systemic hypertension
Carotid stenosis
Pregnancy
Renal disease and anaemia
how is diabbtetic retinopathy classified
Classification of DR
Background (BDR)
Mild, moderate, severe, very severe BDR
Diabetic macular oedema (clinically significant macular oedema-CSMO)
Proliferative DR (PDR)
Early, high risk, advanced PDR
features of diabetic retinopathy (intraretinal changes)
Intra-retinal changes
Microaneurysms (indistinguishable from dot haemorrhages with the ophthalmoscope)
Dot and blot intra-retinal haemorrhages
Retinal oedema
(hard) Exudates
Dilatation and beading of retinal veins
Intra-retinal microvascular abnormalities-IRMA
what is bdr and what features would you see on a fundus image
Background diabetic retinopathy (BDR) refers to the early stage of diabetic retinopathy, which is a complication of diabetes affecting the eyes. In BDR, there are mild changes in the blood vessels of the retina due to prolonged high blood sugar levels.
- exudates (yellow spots)
venous loop (red loop)
blot hamehorrhage /micranyerusms = red dots
what are features of BDR
Nerve fibre layer infarcts or cotton wool spots CWS (sometimes called soft exudates)
Arteriolar abnormalities
Focal areas of capillary non-perfusion
what is loss of vision in BDR due to
Loss of vision in BDR is due to macular oedema (CSMO)
Signs of CSMO are:
Retinal thickening
Exudates approaching fovea
Focal oedema-exudates, microaneurysms
Diffuse oedema
What features would you see on a funuds in macular odema
exudates
fovea
macula
widespread exudates
severe macular odema
optic disc
what are signs that background diapetic retinopthay is progression to proliferative DR
Diffuse intra-retinal haemorrhages and microaneurysms in 4 quadrants
Venous beading in 2 quadrants
IRMA in 1 quadrant
Very severe BDR (defined as any 2 of the above) has 45% chance of progressing to of PDR in one year
what is pre-proliferative dr
Pre-proliferative DR is indicated by:
Severe or very severe BDR plus CWS
CWS indicate poor perfusion and ischaemia
Indicates that other clinical signs of progression should be looked for
Patient is at high risk of developing PDR and should be reviewed more frequently or offered laser treatment
what is proliferative DR charcaterised by
Characterised by:
Pre-retinal fibrovascular proliferation
Begins with:
Fine new vessels (NV) with little fibrous tissue
These increase in size and develop fibrosis
Later regression of NV with fibrosis along back surface of the vitreous
what is PDR
problems are caused by traction of virteous on fibrovascular complexes
this leads to pre-retinal hamehorrhage
virteous haemhorhage (sudden loss of vision)
retinal dettachemnt
iris and angle NV causes secondary reubotic glaucoma (very high ipo pressure)
what is dr treated by
laser
Oedema is caused by leaking vessels
Laser destroys the leaking vessels
We use small numbers of laser applications using green light argon laser
Treatment is directed at leaking microaneurysms in the centre of a ring of exudates
50 micron size, 0.1 second duration
how is dr screened for
If onset of diabetes is <30 years of age, examine retina within 5 years of diagnosis and review annually
If onset of diabetes is >30 years of age, examine retina at diagnosis and then annually
During pregnancy, the retina should be examined once during every trimester
what is the role of anti- VEGF injections
Important part of the treatment for macular edema esp if not responding to laser
Laser still the mainstay for proliferative stage
how are patients reviewd during screening for DR
If no retinopathy or minimal BDR review in 12 months
If mild BDR review in 9 months
If moderate BDR review in 6 months
If severe BDR review in 4 months
If macular oedema refer for laser
If PDR refer for laser
