Diabetes and the Eye Flashcards
What is Diabetic retinopathy?
Diabetic retinopathy is a chronic progressive disease of retina microvasculature associated with prolonged raised blood glucose levels in people with diabetes.
Modifiable risk factors for DR?
- Uncontrolled systemic hypertension
- Uncontrolled blood glucose
- Renal disease
- Hyperlipidemia
- Pregnancy
Consequences of chronic hyperglycemia?
- Capillary wall damage
- E.g. Loss of pericytes, thickening of basement membrane - Hematological changes
- Deformed RBCs and WBCs, ↑platelet aggregation etc. - Microvascular occlusion
- hypoxia
Pathophysiology of DR?
- Damaged vasculature causes ischemia and subsequent release of VEGF by the retina.
- VEGF initially causes abnormal leakage of fluid then later causes proliferation of blood vessels.
- Ischemia and fluid leakage are the primary causes of diabetic retinopathy.
Clinical features of DR?
- Blurred vision
- Floaters
- Sudden painless vision loss
- Later stages progress to irreversible blindness
Classification of DR?
- Non proliferative Diabetic Retinopathy
- The earlier stages of diabetic retinopathy
This stage occurs before development of new vessels - Proliferative retinopathy
- This a more advanced stage where there are abnormal retinal vessels
- May also lead to complications such as vitreous or pre-retinal hemorrhages and retinal detachment - Diabetic maculopathy
Findings observable on dilated opthalmoscopy?
No vs mild vs moderate
- No DR
- no abnormalities - Mild NPDR
- microaneurysms only - Moderate NPDR
- microaneurysms
- dot and blot hemorrhages
- hard exudates
- cotton wool spots
Findings observable in severe NPDR?
Moderate non proliferative DR PLUS
- intraretinal hemorrhages : 4 quadrants
- definite venous bleeding : 2 quadrants
- intraretinal microvascular abnormalities : 1 quadrant
Findings observable in proliferative DR?
severe nonproliferative DR PLUS
- neovascularization
- vitreous/preretinal hemorrhage
Features characteristic of severe non-proliferative DR?
- Venous beading or looping
- Multiple haemorrhages
- Multiple soft exudates or cotton wool spots which indicate areas of ischaemia
- A condition called intra-retinal microvascular abnormalities (IRMA)
Features of proliferative retinopathy?
- New vessels on the optic disc or new vessels anywhere in the retina
- These are fine, fragile vessels that break and bleed easily - Pre-retinal haemorrhage
What is diabetic maculopathy?
This is another subset of diabetic retinopathy.
It occurs in macula
Includes the following;
1. Macula oedema (this is treatable if detected early)
2. Macula ischemia (this is untreatable)
What is macula edema?
- Macular oedema is the most common cause of visual loss in persons with diabetic retinopathy
- Presents with dimness of vision
Signs of macula edema?
- hard exudates
- microaneurysm
- dot or blot hemorrhages
Findings of DME observable on dilated ophthalmoscopy?
retinal thickening
Describe macular ischemia?
- Macula ischemia is very difficult to diagnose on fundoscopy.
- It is confirmed by doing investigation called fluorescein angiography
Ddx for DR?
Branch Retinal Vein Occlusion (BRVO)
Central Retinal Vein Occlusion (CRVO)
Retinal Macro aneurysm
Ocular Ischemic Syndrome Retinopathy
Sickle Cell Retinopathy
Patient hx for DR?
Duration of diabetes
Past glycaemic control (haemoglobin A1c)
Medications (especially insulin oral hypoglycaemics, antihypertensives, and lipid-lowering drugs)
Systemic history (e.g., renal disease,
systemic hypertension, serum lipid levels, pregnancy) *
Ocular history
Physica exam in DR?
Visual acuity
Measurement of intraocular pressure (IOP)
Gonioscopy when indicated (e.g., when neovascularization of the iris is seen or in eyes with increased IOP)
Ocular imaging investigations for DR?
Fundoscopy (Dilated Fundus Exam)
Optical Coherence Tomography (OCT)
Fluorescein Fundus Angiography
Slit-lamp Biomicroscopy
Systemic investigations for DR?
HbA1c
Blood Pressure Measurement
Lipid Profile
Renal Function Tests (e.g., Serum Creatinine, Urinalysis)
Treatment of DR?
- Improve glycemic control if HbA1c > 58 mmol/mol (>7.5%)
- No DR ,PDR /NPDR:
- Follow at recommended intervals with dilated eye examinations and retinal imaging as needed. - Severe NPDR
- Follow closely for development of PDR
- Consider early panretinal photocoagulation. - PDR: Treat with panretinal photocoagulation (PRP).
Drugs used DR?
- Tropicamide eye drops (with phenylephrine)
– for pupillary dilatation during DR screening - Bevacizumab (Avastin)
– for intravitreal injection to treat DME - Triamcinolone acetonide
– for intravitreal injection to treat DME
Treatment of DME?
- Without central involvement - observe for progression
- with central involvement but good visual acuity 6/9 follow up with intravitreal anti-VEGF
- With central involvement with vision loss - intravitreal anti-VEGF
