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
