Diabetic eye disease Flashcards
What are 9 diseases of the eye caused by diabetes?
- blepharitis (inflammation of lid margins)
- Neurotrophic cornea
- Uveitis
- Glaucoma
- Cataracts
- Retinopathy
- Maculopathy
- Optic neuropathy
- Cranial nerve palsies (double vision)
What is meant by neurotrophic cornea?
Nerves supplying the cornea are affected, so cornea becomes neurotrophic (decreased corneal sensitivity) and more prone to getting corneal erosions and scarring
What are the two most important diseases of the eye caused by diabetes?
- Maculopathy
2. Retinopathy
What population group is diabetes the commonest cause of blindness in?
People of working age
Within how many years after diagnosis will all type I diabetics have some retinopathy?
20 years
What proportion of type II diabetics have some retinopathy at diagnosis?
at least 21%
What 2 risk factors produce an increased risk of microvascular complications in type II diabetes, according to the UKPDS study?
- poor glycaemic control
2. high blood pressure
According to the DCCT and EDIC studies, what factor has a strong relationship with retinopathy in type 1 diabetics and what 2 aspects of retinopathy does it influence?
HbA1c; influences onset of retinopathy and its progression
What, according to the DCCT and EDIC studies, will a 10% reduction in HbA1c in type I diabetics lead to?
39% reduction in risk of retinopathy
Which type of diabetes (1 or 2) has a higher rate of retinopathy?
Type 1
What is the relationship between duration of diabetes and incidence of retinopathy?
the longer the duration of diabetes, the higher the incidence of retinopathy
What effect can pregnancy in type I diabetes have on eye disease?
it can very rapidly worsen retinopathy (also type I diabetics more likely to be pregnant than type II diabetics)
What is the effect on eye disease of diabetes patients with other diabetic microangiopathy e.g. nephropathy?
worse retinopathy in these patients; renal failure linked to retinopathy progressing much faster
What may increase the number of hard exudates in the retinas of patients with diabetes?
hypercholesterolaemia
What may double the risk of retinopathy in type I diabetes?
smoking
What is the definition of diabetic retinopathy?
diabetic microangiopathy affecting the retinal blood vessels, resulting predominantly from poor metabolic control and leading to progressive retinal damage which may end in complete visual loss
What is the pathophysiology of microangiopathy in diabetic retinopathy? 3 key elements
- Pericyte death due to hyperglycaemia.
- Basement membrane thickening limiting oxygen transfusion
- Leucostasis causing occlusion (abnormal immune function)
What are the 2 ways that microangiopathy can manifest?
- microvascular occlusion
2. microvascular leakage
What are 4 results of microvascular occlusion?
- cotton wool spots
- capillary closure
- ateriovenous shunts
- neovascularisation
What are 2 results of microvacsular leakage?
- Retinal haemorrhage
2. Retinal exudation
What is the cause of dot haemorrhages?
microaneurysms
What feature on the retina is the earliest detectable sign of diabetes?
dot haemorrhages
What are 6 key visible retinal features of diabetic retinopathy?
- dot haemorrhages/ microneurysms
- blot haemorrhages
- cotton wool spots
- hard exudate
- oedema
- neovascularisation
What causes the microaneurysms in the retina/ dot haemorrhages?
loss of pericytes and outpouching of the capillary wall
What are 4 possible outcomes of dot haemorrhages/ microaneurysms?
- large proportion will spontaneously resolve (50%)
- may burst to form blot haemorrhage
- infarct to form cotton wool spot
- leak to form exudates +/- oedema
Where do blot haemorrhages arise?
from the venous side of the capillaries, deeper in the retina that dot haemorrhages
What 2 things can blot haemorrhages be a sign of?
ischaemia and leakage
What are hard exudates and oedema in the retina caused by?
microvascular leakage; accumulation of lipoproteins between inner plexiform and inner nuclear layers of the retina
What do hard exudates and oedema in the retina look like? Look at a picture
yellow-waxy appearance
What are cotton wool spots in the retina caused by?
areas of retinal ischaemia caused by axoplasmic leakage; sign of localised infarction
What are cotton wool spots in the retina a sign of?
pre-proliferative sign, sign of severe ischaemia
How might hard eudates and oedema appear when visualising the retina?
may be a circinate ring around the source of leakage - i.e. the microaneurysm
What are hard exudates and oedema in the retina often associated with?
swelling of the retina- cystoid macula oedema
Look at an OCT of the retina showing oedema. What does it show us?
dark area under lifted retina is fluid; leaking of aneurysm has caused diabetic macular oedema
What does neovascularisation in the retina indicate?
severe ischaemia
Where might neovascularisation in the retina occur, and how is this termed?
at the optic disc or elsewhere: NVD = new vessels at the disc, NVE= new vessels elsewhere
What are the 2 types of diabetic grading for retinopathy and their purposes?
- Clinical grading: for use in clinic
2. Screening grading: Revised English Diabetic Eye Screening Programme Grading Classification - for screening purposes
What is background retinopathy?
mild form of retinopathy
What is pre-proliferative retinopathy?
stage of severe ischaemia that’s likely to progress to formation of new blood vessels
What are the three categories in which each eye is graded in the Revised English Diabetic Eye Screening Programme Grading Classification?
- Retinopathy
- Maculopathy
- Photocoagulation
What are the 6 ways that retinopathy can be graded in the REDESP Grading Classification?
R0 = no retinoapathy R1 = background retinopathy R2 = pre-proliferative retinopathy R3 = proliferative retinopathy A = active S = stable
What are the 2 ways that maculopathy can be graded in the REDESP grading classification?
M0 absent
M1 present
What are the 2 ways that photocoagulation can be graded in the REDESP grading classification?
P1 added if present, omitted if absent
How would you write background retinopathy with no macular involvement in the REDESP grading classification?
R1 M0
What does R3s M0 P1 indicate in the REDESP grading classification?
Proliferative retinopathy that is stable, with no macular involvement and photocoagulation present
What might R1 background retinopathy involve - 3 things?
- microaneurysms (dot haemorrhages)
- retinal haemorrhages
- exudate
What are 3 possible features of R2 pre-proliferative retinopathy?
- venous beading, looping or reduplication
- intraretinal microvascular abnormalities
- multiple deep, round haemorrahges
What should prompt you to look carefully for the features of pre-proliferative retinopathy?
cotton wool spots present
What are 4 possible features of R3a / proliferative retinopathy?
- New vessels on disc (NVD)
- New vessels elsewhere (NVE)
- Pre-retinal or vitreous haemorrhage
- Pre-retinal fibrosis +/- tractional retinal detachment
What are 4 possible features of R3a / active proliferative retinopathy?
- New vessels on disc (NVD)
- New vessels elsewhere (NVE)
- Pre-retinal or vitreous haemorrhage
- Pre-retinal fibrosis +/- tractional retinal detachment
What are 4 possible features of R2 / pre-proliferative retinopathy?
- venous beading, looping or reduplication
- intraretinal microvascular abnormalities (IRMA) in retina rather than vitreous
- dot and blot haemorrhages, flame shaped haemorrhages
- multiple deep, round haemorrahges
- cotton wool spots
What does R3s / stable proliferative retinopathy look like?
This is post treatment, peripheral retinal laser treatment AND shows stable retina from photograph taken after discharge from hospital eye service
Look at a picture of background retinopathy
haemorrhages, microaneurysms
Look at a picture of pre-proliferative retinopathy. What are 3 key features?
cotton wool spots, blot haemorrhages, flame-shaped haemorrhages
What causes retinal venous beading?
dilation of veins
What are 3 retinal venous abnormalities that occur at the pre-proliferative (R2) stage?
Reduplication, looping, beading
What is pre-retinal haemorrhage?
occurs in proliferative retinopathy, fluid level at bottom of vitreous