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
What causes pre-retinal fibrosis?
In diabetic retinopathy that is severe and advanced, there is the formation of gliotic/ fibrovascular membranes
Look at pictures of pre-retinal haemorrhage, new vessels at the disc and new vessels elsewhere, pretinal fibrosis and ractional retinal deachment
see diabetic eye disease document if needed
What are the symptoms of diabetic retinopathy affecting the peripheral retina?
tends to be asymptomatic
What causes diabetic maculopathy?
microvascular damage within the retina
What are likely the symptoms of diabetic maculopathy?
fine vision disturbance (much more likely to notice than peripheral retinopathy)
What is the leading cause of blindness in diabetics?
Diabetic maculopathy
What are the 2 type of maculopathy that it can be classified into?
- exudative - leakage
2. ischaemic
What are 2 types of exudative maculopathy?
- focal part of macula affected
2. diffuse - diffuse breakdown of blood-retinal barrier with leakage throughout retina
What causes ischaemic maculopathy?
Dropout of capillaries in macula - can be seen on FFA
How can ischaemic maculopathy be shown using imaging techniques?
Fundal fluorescein angiography - shows dropout of capillaries in macula
What are the 2 levels of maculopathy grading?
- Level M0: no maculopathy
2. Level M1: maculopathy
What 4 things count as M1/ maculopathy present?
- exudate within <1 DD (disc diameter) of fovea centre
- circinate/ group of exudates <22 DD of fovea centre
- Retinal thickening within 1 DD of the centre of the fovea (if stereo available)
- any microaneurysm or haemorrhage within 1 DD of the centre of the fovea only if associated with a best visual acuity of <6/12 (if no stereo)
Look at an FFA showing ischaemic maculopathy
macula appears dark
What is the best way to visualise macular oedema in diffuse exudative maculopathy?
OCT
What are the 2 levels of photocoagulation grading?
- Not recorded: no laser scars
2. Level P: macular laser scars, scatter laser scars in periphery
How can severe diabetic retinopathy lead to rubeosis?
VEGF causes new blood vessel growth, and the VEGF can diffuse forwards to form vessel growth in the iris due to ischaemia in the anterior retina and iris.
What 2 things can occur as a result of new vessel growth in the iris in rubeosis?
the new vessels can bleed, causing a hyphaema or glaucoma
What are 4 types of diabetic eye disease that can occur as a result of advanced diabetic eye disease, as a consequence of new vessel growth?
- Rubeosis
- Vitreous haemorrhage
- Neovascular glaucoma
- Retinal detachment
How can vitreous haemorrhage occur in severe diabetic eye disease?
bleeding from new vessels due to ischaemia
What difficulty on examination does vitreous haemorrhage cause?
blocks red reflex making fundoscopy difficult
What key symptom is there in vitreous haemorrhage?
reduces patient vision
What is the treatment for vitreous haemorrhage in severe diabetic eye disease?2 elements
needs urgent laser to reduce ischaemia; if persistent may require surgery
What can cause neovascular glaucoma in severe diabetic eye disease?
New blood vessels growing on iris/irido-corneal drainage angle, blocks drainage of aqueous
What are the symptoms of neovascular glaucoma?
Very high intraocular pressure causes a painful eye
What is the prognosis like for neovascular glaucoma secondary to severe diabetic eye disease?
Very difficult to treat therefore poor prognosis
How can severe diabetic eye disease lead to retinal detachment?
retinal haemorrhage due to new vessels causes fibrotic scarring. contraction of adherent fibrotic scars pull on the retina, causing detachment and ultimately blindness
What might be a treatment option for retinal detachment secondary to severe diabetic eye disease?
might be amenable to surgery
What are 3 main treatment options for diabetic retinopathy?
- laser
- intravitreal injections: steroids, anti-VEGF
- surgery - if advanced
What is the mainstay of treatments for diabetic retinopathy?
Laser
How does laser treatment work to treat proliferative retinopathy?
- Laser light is absorbed by the retina, creating heat.
- Heat destroys the photoreceptors, reducing the oxygen demand
- therefore reduces ischaemia and release of pro-angiogenic factors
What is the type of laser treatment that is used for proliferative retinopathy in diabetes?
Panretinal photocoagulation (PRP)
What is the laser treatment for focal exudative maculopathy?
Focal laser
What is the laser treatment for diffuse exudative maculopathy?
Macular grid
Is there any laser treatment available for ischaemic maculopathy?
no
How does panretinal photocoagulation work?
reduces retinal ischaemia by destroying the peripheral retina, reduces stimulus for new vessel growth; relies on sacrificing the peripheral retina for the central vision
What is one of the disadvantages of panretinal photocoagulation?
may have a very reduced visual field and be unable to drive (can also be uncomfortable for patients, may need multiple laser sessions)
What is the purpose of using laser treatment for focal/diffuse exudative maculopathy?
Used to try to reduce exudative leakage and oedema
How is laser treatment used for focal exudative maculopathy?
focal approach: leakage from specific microaneurysm causes the focal maculopathy, so small number of laser spots applied
How is laser treatment used for diffuse exudative maculopathy (i.e. no obvious point of leakage)?
Gentle laser around centre of macular, laser applied more diffusely in a grid pattern called a Macular Grid
What can heavy burns during laser treatment for diabetic maculopathy lead to?
blind spots
What are 2 complications of focal laser (for focal exudative maculopathy)?
- Heavy macular burn can cause blind spots
2. small scars may slowly enlarge over time
What are 4 complications of PRP (panretinal photocoagulation)?
- reduced visual field - patient must notify DVLA
- reduced night vision
- inadvertent macular burn and blind spot (e.g. if patient inadvertently looks at laser can damage fovea)
- Bleeding - may occur due to regression of blood vessels
Who must patients notify after having PRP due to the reduced visual field?
DVLA
What are the 3 types of intravitreal injections commonly used to treat exudative maculopathy? Chemical name and trade name
- Bevacizumab (Avastin)
- Aflibercept (Eylea)
- Ranibizumab (Lucentis)
What are two types of steroid intravitreal injections?
- Triamcinolone
2. Steroid implants e.g. Osurdex
What type of diabetic eye disease are intravitreal injections most commonly used for?
exudative maculopathy
Where anatomically are intravitreal injections administered?
Between the retina and the lens (invasive)
What is the laser treatment for focal exudative maculopathy?
Focal laser
What is the laser treatment for diffuse exudative maculopathy?
Macular grid
What is the mechanism of action of anti-VEGF agents generally?
block VEGF-A, reducing the stimulus for neovasuclarisation
How does panretinal photocoagulation work?
reduces retinal ischaemia by destroying the peripheral retina, reduces stimulus for new vessel growth; relies on sacrificing the peripheral retina for the central vision
What is one of the disadvantages of panretinal photocoagulation?
may have a very reduced visual field and be unable to drive (can also be uncomfortable for patients, may need multiple laser sessions)
What are 2 things that anti-VEGF injections?
- treat exudative maculopathy (may require multiple injections)
- temporarily reduce new vessels before surgery or laser (more permanent treatment)
How is laser treatment used for focal exudative maculopathy?
focal approach: leakage from specific microaneurysm causes the focal maculopathy, so small number of laser spots applied
How is laser treatment used for diffuse exudative maculopathy (i.e. no obvious point of leakage)?
Gentle laser around centre of macular, laser applied more diffusely in a grid pattern called a Macular Grid
What can heavy burns during laser treatment for diabetic maculopathy lead to?
blind spots
What are 2 complications of focal laser (for focal exudative maculopathy)?
- Heavy macular burn can cause blind spots
2. small scars may slowly enlarge over time
What are 4 complications of PRP (panretinal photocoagulation)?
- reduced visual field - patient must notify DVLA
- reduced night vision
- inadvertent macular burn and blind spot (e.g. if patient inadvertently looks at laser can damage fovea)
- Bleeding - may occur due to regression of blood vessels
Who must patients notify after having PRP due to the reduced visual field?
DVLA
What are the 3 types of intravitreal injections commonly used to treat exudative maculopathy? Chemical name and trade name
- Bevacizumab (Avastin)
- Aflibercept (Eylea)
- Ranibizumab (Lucentis)
What are 2 specific things that vitrectomy is used for in severe diabetic retinopathy?
- Vision-threatening tractional retinal detachment
2. Persistent vitreous haemorrhage- reduces vision or precludes laser treatment
What are the 3 aims of vitrectomy treatment?
- removal of vitreous gel
- division of fibrovascular bands
- further laser - endolaser
Where anatomically are intravitreal injections administered?
Between the retina and the lens (invasive)
What are 4 complications of intravitreal injections?
- Endophthalmitis
- haemorrhage
- cataract (if damage to lens)
- retinal detchament (if damage to retina)
What can be said about the overall safety of intravitreal injections?
Generally very safe
What are the mechanisms of action specifically for each of the three common anti-VEGF agents?
- Aflibercept (Eylea) - receptor fragment
- Bevacizumab (Avastin) - antibody
- Ranibizumab (Lucentis) - antibody fragment
How frequently are anti-VEGF IV injections given
monthly, sometimes less frequently
Why are anti-VEGF injections only a temporary treatment for diabetic retinopathy?
treats the result but not the cause of ischaemia
What was one of the first used steroids for diabetic maculopathy?
Triamcinolone
What type of photography is performed for diabetic retinopathy screening?
digital fundus photography
Of the two commonly used steroids for diabetic macular oedema, which are licensed?
- triamcinolone - unlicensed for diabetic macular oedema
2. Ozurdez (dexamethasone) - biodegradable implant , lincensed steroid for macular oedema
How long does Ozurde last for?
this biodegradable implant lasts 6 months
What are 2 intravitreal steroid complications that there is a significant risk of?
- glaucoma
2. cataract
When is surgical vitrectomy used?
Diabetic retinopathy
What are 2 specific things that vitrectomy is used for in severe diabetic retinopathy?
- Vision-threatening tractional retinal detachment
2. Persistent vitreous haemorrhage- reduces vision or precludes laser treatment
What are 2 reasons why persistent vitreous haemorrhage might be treated with vitrectomy?
- reduces vision
2. precludes laser treatment
Why might patients develop significant retinopathy before presenting to hospital eye services?
diabetic retinopathy affecting the peripheral retina is usually asymptomatic
When are 2 scenarios when someone with diabetic retinopathy might present?
- vitreous haemorrhage
2. tractional retinal detachment
Why is it a problem if patients with diabetic retinopathy only present once retinal detachment or vitreous haemorrhage have occurred?
by this stage, difficult to treat with good visual outcome
Which body is diabetic retinopathy screening centrally coordinated and led by?
NHS Diabetic Eye Screening Programme (NHS-DESP)
What is the screening programme for diabetics?
All diabetics over age of 12 have annual photos taken by Diabetic Retinopathy screening service
Who views the annual retina photos taken as part of diabetic retinopathy screening, and what do they do?
Trained personnel, grade the diabetic retinopathy (if present) and refer patients who have evidence of pre-proliferative diabetic reinopathy into hospital eye services for treatment before proliferative retinopathy
What type of photography is performed for diabetic retinopathy screening?
digital fundus photography
How many local screening services for diabetic retinopathy screening are there overseen by the Health Authorities? What do they ensure?
over 80; central guidelines and quality assurance; primary, secondary, tertiary grading and 10% QA
When else are patients referred to hospital eye services after digital fundus photography screening, in addition to pre-proliferative retinopathy?
if they show diabetic maculopathy that is threatening vision but hasn’t yet damaged vision (can be given e.g. focal laser treatment)
What 2 important factors are vital in preventing retinopathy/preventing progression in diabetes?
maintenance of low 1) HbA1c and 2) low BP (note: sometimes rapid improvement can cause worsening of diabetic retinopathy - good to have overall good control)
