Diabetes: Eye Disease

Related Subjects: Type 1 DM | Type 2 DM | Diabetes in Pregnancy | HbA1c | Diabetic Ketoacidosis (DKA) Adults | Hyperglycaemic Hyperosmolar State (HHS) | Diabetic Nephropathy | Diabetic Retinopathy | Diabetic Neuropathy | Diabetic Amyotrophy | Maturity Onset Diabetes of the Young (MODY) |

Almost all individuals with type 1 diabetes, and most of those with type 2 diabetes, will have some degree of retinopathy after 20 years but for most will be mild

About

• Type 1 diabetes affects 50% by 10-15 years
• Type 2 diabetes affects 50% by 15 years
• Blindness is preventable

Diagrams

Aetiology

• Increased vascular endothelial growth factor production
• This is initiated by hyperglycaemia-induced capillary occlusion
• Increased Retinal vascular endothelial growth factor
• Increased capillary permeability with retinal oedema
• Stimulates angiogenesis with new vessel formation.

Screening

• All Diabetics should have regular fundoscopy with dilated pupils which can reduce damage with early treatment
• Diabetic retinopathy in need of retinal photocoagulation is often symptomless
• Most screening can be by digital imaging photography with referral to ophthalmologist as necessary

Classification

• I. Background Retinopathy - no symptoms
  • Microaneurysm - dots are small aneurysms and can be seen by angiography
  • Micro haemorrhage - blots
  • Hard exudates - lipids : not affecting macula
  • Hard exudates near macula: refer to consider for intravitreal triamcinolone
• II. Mild non proliferative - central visual loss
  • Leakage and oedema in macular area
  • Hard exudates within one disc margin of macula
  • need a referral to Ophthalmology service
• III. Severe non/pre proliferative - No symptoms
  • Venous abnormalities e.g. beading
  • Large blot haemorrhages
  • Cotton wool spots (small ischaemic/infarcted areas)
• IV. Proliferative - No symptoms but needs urgent referral
  • New vessel at disc
  • New vessel elsewhere
• Maculopathy: may have reduced acuity; Urgent referral
  • Macular oedema: laser, intra vitreal steroids, or anti-angiogenic agents may be needed
• Advanced Proliferative eye disease (Urgent referral)
  • Untreated will cause severe visual impairment through recurrent vitreous haemorrhage and retinal detachment. Pan-retinal laser photocoagulation therapy is extremely effective at preserving vision if applied before complications set in.
  • Extensive fibrovascular proliferation - visual loss and blindness
  • Retinal detachment
  • Vitreous haemorrhage
  • Glaucoma
  • Cataracts: juvenile snowflake form, or senile
  • Rubeosis iridis: New vessels on iris: occurs late and may lead to glaucom

Management

• Historically, laser therapy was used empirically to ablate the retina extensively outside the macula. However, this caused secondary optic atrophy and night blindness (nyctalopia) and so difficult to drive at night. Modern day laser use is lighter and ore focused on sites of ischaemia. Drivers need to inform DVLA.
• Intravitreal injections of anti-vascular endothelial growth factor (e.g. ranibizumab, aflibercept, bevacizumab) also cause temporary regression of proliferative retinopathy
• Macular oedema: extrafoveal oedema often resolves spontaneously. The use of intravitreal injection therapy rescues vision in 50% of those treated regardless of the mechanism of oedema. This means a much less role for laser.