Diabetic Eye Disease

Retinopathy

• Damage to the retina

Pathophysiology

• Early stages of retinopathy, rated from mild-severe (with severe being last stage before proliferative retinopathy)

• Damage to the wall of small vessels cause microaneurysms and then intraretinal haemorrhages (dot, blot, flame)

• Leaked blood leaves behind hard exudates (lipid breakdown products)

• Micro-infarcts (ischaemia) due to occluded vessels cause cotton wool spots

• Laser therapy in severe NPDR may help prevent long-term visual loss

• Blockage of blood vessels leads to areas of non-perfusion and ischaemia

• Ishchaemia in these areas cause the release of vascular growth factors e.g. VEGF which cause new blood vessels to grow in the retina (neovascularisation)

• IRMA - abnormalities of blood vesssels/precursor to neovascularisation but blood vessels are patent (not leaking)

• Vitreous haemorrhage can occur of the new blood vessels leading to sudden loss of vision

• Lifetime risk of developing proliferative retinopathy in a diabetic patient is ~35%

Retinal screening

Grading of retinopathy and maculopathy

Retinopathy management

• Laser - panretinal photocoagulation
• Reduces oxygen requirement of the retina so reduces the ishchaemia that is driving the retinopathy

• Vitrectomy in a vitreal haemorrhage

Diabetic macular oedema (maculopathy)

• Macular oedema involves clinically significant retinal thickening and oedema involving the macula, hard exudates and macula ischaemia

• May occur in all stages of NPDR and PDR

Investigations

• Optical coherence tomography if indicated from retinal screen

Management

• Intravitreal anti-VEGF (anti-vascular endothelial growth factor)

Other eye pathologies in diabetes

• Cataract - clouding of the lens, develops earlier in people with diabetes
• Increased sugar contents in lens
• Conversion of glucose to sortbitol
• Altered osmotic gradients → swelling and fibre disruption

• Glaucoma - increase in fluid pressure in the eye leading to optic nerve damage, 2x more common in diabetes
• Rubeotic glaucoma - new vessel formation forming angle (rare and late complication)

• Acute hyperglycaemia causes visual blurring (reversible)