Diabetic eye disease: clinical features and classification Flashcards
what causes T1 DM
Body loses ability to produce insulin (not a lifestyle type)
what causes T2 DM and how is it controlled
Ineffective use of insulin (insulin resistance), or insufficient insulin production
Controlled with diet, exercise, tablets, insulin
what lifestyle factors is T2 DM strongly associated with
what are the 2 non-modifiable risk factors
Strongly associated with:
obesity
lack of physical activity
smoking
Non modifiable risk factors:
- Race: Prevalence increased ~6x in South Asian and ~3x in Afro-Caribbean people compared to Caucasian
- Risk increases with age
what type of disease is diabetic retinopathy (DR)
what is it the leading cause of
Microvascular + neurodegenerative retinal disease
Leading cause of blindness in working population
what 2 locations of DR can there be
peripheral (R)
or
macular (M)
what are the 2 sight-threatening forms of DR
proliferative DR and macular oedema
what 2 things can DR be
non proliferative no new blood vessels
proliferative new blood vessels
= higher risk of sight loss
what 4 things is the risk of DR (and risk of progression) related to
Duration DM - longer more likely to get
Control of DM (Higher HbA1c [glycated haemoglobin] indicates poor control)
Type of diabetes (77% type I vs 25% type II)
Hypertension
what is the main classification system used
how is it used
NHS Diabetic Eye Screening Programme (DESP)
Each eye is given an R (peripheral retinopathy) and M (maculopathy) grade
who should be registered on the NHS screening programme
Everyone with diabetes aged over 12 years
if you see a px above 12 y/o with DM and is not on the scheme, you need to refer then to their GP to get registered
what are the 5 fundus signs of R1 classification of peripheral DR
and what is required to do if you see this
Microaneurysm(s)
Retinal haemorrhage(s) not within definition of R2
Exudate (in absence of referable R2 features)
Venous loop(s) (in absence of referable R2 features)
Cotton wool spots in presence of other R1 features
Background DR
referral not required - as don’t need treatment
what does a single microaneurysm diagnose what is their appearance and what size what are they smaller than where abouts are they usually located which layer of the retina are they in
Single microaneurysm diagnoses DR Dark red dots, sharp border, less than 125μm in diameter Smaller than vein diameter at ONH Usually temporal to macula Inner nuclear layer
which vessels are micro aneurysms of
of the capillaries - small vessels
aneurysm = weakness of a BV wall which causes the BV wall to balloon out
what causes dot haemorrhages
what are they larger than and what are they smaller than
what are they not different to in appearance when using ophthalmoscopy/fundus photography
Capillaries in inner plexiform layer are ruptured
Larger than microaneurysms but smaller than blot haemorrhages
Not reliably differentiated from micro aneurysms based on using ophthalmoscopy / fundus photography
where are blot haemorrhages found in the retinal layers
what is their appearance
what are these a sign of
how many of these are classed as severe, as R1 and as R2
Deeper haemorrhages of capillaries between IPL and INL
Larger, darker than dot haemorrhage
Often sign of local ischaemia especially if temporal
more than 20 = severe. If only a few = R1, if many = R2
where in the retinal layer are flame shaped haemorrhages found
what are they often seen with
which 3 other eye diseases are they seen in
Superficial within nerve fibre layer = more feathery appearance
Often with cotton wool spots
Also seen in systemic hypertension, glaucoma, vein occlusion (so can’t immediately say flame haemorrhage is DR)
what are exudates
which retinal layer are they found
what will px’s with this also have
what can happen to them
Lipid and lipoprotein leaked from capillaries
in OPL or IPL
= seen as hard exudates - are yellow/white deposits
px will also have oedema with this
Can reabsorb spontaneously/post laser treatment
what is oedema
how can you not see oedema in clinic and how can you see it
what signs may you see in association with haemorrhages and micro aneurysms
what sign is the best guide to oedema
Accumulation of fluid within retina
can’t see if no stereo e.g. monocular view so OCT views is better to see
May see cysts and greying in association with haemorrhages and microaneurysms
Best guide to oedema is presence of exudate
what is the appearance of cotton wool spots like and which layer of the retina are they found
what is CWS caused by
what can happen to them
Fluffy white lesions in RNFL (Often found where the RNFL is thickest i.e. posterior pole)
Caused by focal or diffuse inner retinal ischaemia, disrupting RNFL axonal transport
Reabsorb but can take 6+ months (if theres recovery from the ischamia)
how can you see that cotton wool spots are at the top layers of the retina
and other what R1 sign is found in the deeper layers within the retina
cotton wool spots obscure the blood vessels underneath = at RNFL
exudates are deeper within the retina
what is a venous loop
what is this a sign of
Abrupt curving away from normal path of vessel
Sign of retinal ischaemia
what abbreviation best describes/sums up the features of R1 Background DR and what does it stand for
HOME
Haemorrhage
Oedema
Micro aneurysms
Exudate
when do cotton wool spots not count as R1 DR
and when do they count as R1
R1 if present with no other signs
but if present with haemorrhages / exudates, form a part of R1
what should you do if you see a patient with background R1 DR features
refer them to the GP for diabetic screening programme if they don’t currently get it done
but they’re not going to be treated
what are the 4 fundus signs of pre-proliferative R2 DR and what do you need to do if you see this
Multiple blot haemorrhages
Venous beading
Venous reduplication
Intra-retinal microvascular abnormality (IRMA)
refer to ophthalmologist, soon within a 4 week period
what are the appearance of blot haemorrhages in R2 and how does this compare to R1
R2 - multiple blot haemorrhages
R1 - 1/2 blot haemorrhages
what does IRMA (Intraretinal Microvascular Anomaly) indicate
Indicates retinal ischemia
what are the 4 features in the appearance of IRMA (Intraretinal Microvascular Anomaly) like
Mimic new vessels but are thought to represent dilated capillaries in area of occlusion
Variable calibre (thickness), odd branching patterns and sharp angles Appear to run from arterioles to venules
No crossing of major vessels
Don’t leak
what is IRMA (Intraretinal Microvascular Anomaly) not
but what do they do in response to ischaemia
They’re not new blood vessels
But because of ischaemia, they dilate and try to bring more blood into the area (i.e. they just adapt) as a response
how is IRMA (Intraretinal Microvascular Anomaly) different from new blood vessels
they won’t cause haemorrhages or leak exudates
they are just normal capillaries that have adapted to ischaemia
what is the most reliable sign in R2 of ischaemia
venous changes
what are the 3 main appearances that describes venous changes as found in R2
Veins variable calibre (changes in thickness along its length)
Segmented, beaded, dilated
Beading = localised areas increased calibre
Occluded vessels
what are the 4 fundus signs of R3 proliferative retinopathy and what will you do if you see this
New vessels on disc (NVD)
New vessels elsewhere (NVE)
Pre-retinal or vitreous haemorrhages
Pre-retinal fibrosis ± tractional retinal detachment
will refer px urgently - px is at risk of sight loss quite soon
what causes the new vessel growth in Active Proliferative (R3a) DR
caused by endothelial cell proliferation in response to up regulation of growth factors produced by RPE in ischaemic retina (response to hypoxia)
The thought is that the retina is experiencing areas of hypoxia, or is “under-nourished”. In an effort to compensate for this problem, the eye grows new vessels in the areas lacking circulation
what 6 features describes the new vessels in active proliferative R3a
New vessels are very fragile, and tend to leak and bleed (so aren’t very affective)
Often loop back on themselves and widen in diameter
Will cross major vessels (unlike IRMA)
Often form ‘blossom’ of numerous vessels in a patch together - new BV’s bending back on themselves
Obscure underlying lesions therefore on top of retina, not within it (unlike IRMA) as they grow on top of the retina rather than in it
Eventually grow into vitreous
what is there a high risk of in Active Proliferative (R3a) and what is this associated with
when this is seen what action is required
High risk of vitreous haemorrhage
Associated with fibrous traction on retina
Requires urgent referral
where about do new vessels at the disc appear on the retina in Active Proliferative (R3a) DR
when is it usually a R2 feature
what risk is there if the NVD is untreated
New vessels on or within 1 DD from ONH
Rest of retina = usually R2 features
50% risk blindness in 5y if untreated
where do new vessels elsewhere appear in Active Proliferative (R3a)
what is there appearance like
what are they commonly associated with
what risk is there if the NVE is untreated and what is it’s prognosis slightly better than
New vessels more than 1 DD from ONH
Often temporal to macula, sometimes nasally
Fine friable vessels usually arising from large veins
Commonly associated with R2 venous changes
30% risk blindness in 5 years if left untreated
prognosis slightly better than NVD
if a pre-retinal/vitreous haemorrhage as seen in Active Proliferative (R3a) DR is seen:
what must you assume
when does this occur
If present, assume new vessels
Occur when new vessels grow forward from retina, cross the subhyaloid / preretinal space, and enter the vitreous
what will a patient who has a pre-retinal/vitreous haemorrhage as seen in Active Proliferative (R3a) DR, what symptoms will they report
how will it appear when you view it
Px reports sudden visual loss or sudden onset of dark floaters
Appears dark, may completely block view of the retina
in what case will a pre-retinal/vitreous haemorrhage as seen in Active Proliferative (R3a) DR take a long time to clear
what is the risk of this pre-retinal/vitreous haemorrhage if it is left untreated
Takes long time to clear if erythrocytes break into vitreous body (months/years)
Untreated, 30 % of eyes will be blind within 1 year of first vitreous haemorrhage
what causes the vessels in pre-retinal/vitreous haemorrhage as seen in Active Proliferative (R3a) DR to rupture
These vessels rupture easily, associated fibrous tissue contracts and tears them, as does the normal shrinkage of the vitreous with age
what is the difference in appearance of a pre-retinal haemorrhage and a vitreous haemorrhage and why
pre-retinal haemorrhage often has a flat top due to red blood cells settling down due to gravity when a px is sit upright
vitreous haemorrhage does NOT have a flat top appearance - it looks more disorganised
what is fibrous tissue associated with/caused by
what can the contraction of this fibrous tissue cause
Fibrous tissue associated with new blood vessels and with previous vitreous / pre-retinal haemorrhage
Contraction of fibrous tissue can pull retina to cause tractional retinal detachment (TRD)
when may fibrous tissue be visible
how may the retina appear as a result of this fibrous tissue
Pale fibrous tissue may be visible
Retina may appear wrinkled (traction lines), bumped and folded, or tears may be visible
what symptom is the tractional retinal detachment caused by due to the contraction of the fibrous tissue
what procedure is carried out to prevent the occurrence of a TRD
TRD associated with sudden loss vision
Vitrectomy carried out to prevent TRD
what 2 things can a haemorrhage cause
scar tissue forming
or
fibrous tissue growing along the new blood vessels
what causes Rubeosis Iridis and what may this lead to
Severe retinal hypoxia (widespread proliferative DR) may lead to growth factors producing new vessel growth on iris or in angle
Can lead to neovascular glaucoma due to fibrovascular tissue blocking angle of drainage = dramatic sudden increase in pressure - the eye is often extremely painful
what must you do if you see Rubeosis Iridis in your px
refer them asap as an ocular emergency
what 2 things is R3s DR
Stable post treatment
Evidence of Peripheral Retinal Laser Treatment
AND
Stable retina compared to photograph taken at or shortly after discharge from the Hospital Eye service (HES)
what is the DESP classifications of maculophathy in DR
M0
M1
what are the 2 features of M0
No maculopathy
Non-referable maculopathy (MAs or haems within 1DD and
vision better than 0.3 LogMAR/ Snellen 6/12)
what is classed as a non referable maculopathy
M0
MAs or haems within 1DD and
vision better than 0.3 LogMAR/ Snellen 6/12
list 4 clinical features of M1 and what does this require
Exudate within 1 disc diameter of the centre of the fovea
Circinate or group of exudates within the macula
Retinal thickening within 1 DD of the centre of the fovea
Any microaneurysm or haemorrhage within 1 DD of the centre of the fovea ONLY if associated with VA worse than Snellen 6/12 or 0.5
requires referral - Requires treatment: Clinically Significant Macular Oedema (CSMO)
Needs laser or anti-VEGF treatment
what does the DESP define as the macular region
that part of the retina which lies within a circle centred on the centre of the fovea whose radius is the distance between the centre of the fovea and the temporal margin of the disc
= a large area and not just the foveal region
in M1, what is the Circinate or group of exudates within macula usually associated with and what else may you find with it
Usually associated with oedema
May find accompanying aneurysms (source of leak)
in M1, what is the Retinal thickening within 1 DD of the centre of the fovea:
due to
how can it be easier to spot clinically
Due to macular oedema
Easier to spot using OCT or stereoscopic viewing e.g. volk
in M1, what does the retinal thickening/oedema have to be in order to be immediately referable
has to be stretched over the 1DD
in M1, what type is the retinal oedema seen within 1 DD in nature
often ‘cystoid’ in nature
when is it only classed as M1 if you see any microaneurysm or haemorrhage within 1 DD of the centre of the fovea
ONLY if associated with VA worse than Snellen 6/12
what is the DESP classifications of Photocoagulation Scars
P0
P1
what feature does P0 have
No photocoagulation (laser scars)
what 2 features does P1 have
Presence of photocoagulation scars:
Evidence of focal/grid laser to macula
Evidence of peripheral scatter laser
seen as white or with a bit of pigmentation
when will you Refer your px to HES - To be seen soon (within 4 weeks)
list 4 reasons
R2 (pre-proliferative changes)
Unexplained retinal findings
M1 (referable maculopathy)
Unexplained drop in VA
when will you Refer your px to HES -To be seen urgently (within 1 week)
New vessels formation
when will you Refer your px to HES -To be seen as an emergency
list 4 reasons
Sudden loss of vision
Evidence of retinal detachment
Pre-retinal/vitreous haemorrhage
Rubeosis iridis
how will you manage a px with P1 and when will you refer them
Post treatment: annual review
Refer to HES: if not recorded before
