diabetic%20retinopathy
DIABETIC RETINOPATHY
Diabetic retinopathy is an abnormality of the microvasculature of the retina that occurs to almost all patients with chronic diabetes mellitus.
It is one of the leading cause of blindness worldwide and principal cause of impaired vision in patients aged 25-75 years of age.
The abnormality causes microaneurysms, retinal hemorrhages, lipid exudates, macular edema & neovascular vessel growth that may lead to blindness.

Introduction

  • Diabetic Retinopathy (DR) is a progressive retinal disorder that occurs to almost all patients w/ chronic diabetes mellitus (DM)
  • One of the leading causes of blindness worldwide
  • Principal cause of impaired vision in patients aged 25-75 yrs old
  • Leading complication of DM
  • Earliest visible manifestations are microaneurysms & 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 & initially by increases in retinal blood flow
    • Resulting widened venular caliber is a marker of the severity of DR

Signs and Symptoms

Clinical Presentation

  • Initial clinical signs of DR are:
    • Thickening of the retinal basement membrane
    • Microaneurysms or hypercellular outpouchings of retinal capillaries w/ weakened walls due to pericyte loss
    • Leakage of lipid & 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 NPDR that includes: extensive retinal hemorrhages/microaneurysms, venous beading & intraretinal microvascular abnormalities (IRMA)
    • Vitreous or preretinal hemorrhage
  • The basic changes in the retinal vessels are:
    • Abnormal permeability & vascular occlusion w/ ischemia
    • Subsequent neovascularization
  • Typical retinal microvascular lesions of DR are:
    • Microaneurysms
    • Hard exudates
    • IRMA
    • New vessels or neovascularization
    • Hemorrhages
    • Cotton wool spots
    • Venous beading
    • Fibrous tissue

Risk Factors

  • Visual loss from DR 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 DR are the duration of diabetes & the severity of hyperglycemia; other risk factors include pregnancy, puberty, cataract surgery, medical conditions (eg hypertension, hyperlipidemia)
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