Introduction
- A progressive retinal disorder that occurs in almost all patients with chronic diabetes mellitus (DM)
- One of the leading cause of preventable vision impairment and blindness worldwide
- Principal cause of impaired vision in patients aged 25-74 years
- Leading complication of DM
- Earliest visible manifestations are microaneurysms and hemorrhages
Pathophysiology
- Believed to be a result of different biochemical changes (eg aldose reductase, protein glycation, protein kinase C activation, angiotensin enzyme expression, vascular endothelial growth factor expression, etc) accompanied by blood retinal barrier increased permeability and initially by increases in retinal blood flow
- Resulting widened venular caliber is a marker of the severity of diabetic retinopathy (DR)
Signs and Symptoms
Clinical Presentation
- Initial clinical signs of diabetic retinopathy are:
- Thickening of the retinal basement membrane
- Microaneurysms or hypercellular outpouchings of retinal capillaries with weakened walls due to pericyte loss
- Leakage of lipid and proteinaceous material (hard exudates)
- Signs that would lead to visual impairment:
- Presence of macular edema
- Presence of new vessels at the optic disc (NVD) or new vessels elsewhere in the retina (NVE)
- Manifestations of severe that includes: Extensive retinal hemorrhages/microaneurysms, venous beading and intraretinal microvascular abnormalities (IRMA)
- Vitreous or preretinal hemorrhage
- The basic changes in the retinal vessels are:
- Abnormal permeability and vascular occlusion with ischemia
- Subsequent neovascularization
- Typical retinal microvascular lesions of diabetic retinopathy are:
- Microaneurysms
- Hard exudates
- IRMA
- New vessels or neovascularization
- Hemorrhages
- Cotton wool spots
- Venous beading
- Fibrous tissue
Risk Factors
- Visual loss from diabetic retinopathy is caused either by:
- Macular edema
- Vitreous hemorrhage
- Neovascular glaucoma
- Macular capillary nonperfusion
- Distortion or traction detachment of the retina
- The major risk factors in the development of diabetic retinopathy are the duration of diabetes and the severity of hyperglycemia
- Other risk factors include pregnancy, puberty, cataract surgery, medical conditions (eg hypertension, hyperlipidemia)
- Associated with poor control of blood glucose, blood lipids and blood pressure