DIABETIC RETINOPATHY

    Dr Ivan Ho
    Sydney Eye Hospital

     

     
Epidemiology

     
Epidemiology - Diabetes Mellitus
 
  • 110 million people with DM worldwide in 1994

  • Projected incidence in 2010 is 221 million worldwide per year

  • Prevalence of DM in general population is ~3-4%
Amos et al., Prevalence studies of diabetic complications 1997; National Institutes of Health, www.niddk.nih.gov

 
Epidemiology - Diabetic Retinopathy
 
  • 110 million people with DM worldwide in 1994

  • Projected incidence in 2010 is 221 million worldwide per year

  • Prevalence of DM in general population is ~3-4%
Amos et al., Prevalence studies of diabetic complications 1997; National Institutes of Health, www.niddk.nih.gov

 
Diabetic Retinopathy (DR)
 
  • Leading cause of blindness in patients aged 20-64 years in developed nations

  • After 20 years of DM, 99% of type 1 and 60% of type 2 have some retinopathy

  • Exact mechanisms leading to development of DR are not understood

WESDR; Arch Ophthalmol 1984;102:520-526

 
Pathogenesis

     
Pathogenesis of DR
 
  • Thickening of capillary basement membrane
  • Loss of capillary mural pericytes
  • Basement membrane hypertrophy and endothelial cell loss
  • Breakdown of blood-retinal barrier
  • Earliest clinical sign of DR is presence of microaneurysms
  • Retinal ischaemia → lipid exudation, haemorrhage and release of pro-angiogenic factors
  • Neovascularisation → haemorrhage → fibrosis and traction detachment

 
Pathogenesis of DR
 

    Left: Blood vessels show tortuosity and microaneurysm formation
    Right: Capillary closure on phase microscopy

 
Histopathology
 

  • Capillary microaneurysm associated with an area of hemorrhage

  • Cotton-wool spot: Precapillary arteriole occlusion causing microinfarction of the nerve fiber layer

 
Risk Factors

     
Risk Factors for DR
 
  • Duration of diabetes
        Key factor in DR development

  • Control of diabetes
        Key factor in DR progression

  • HT, Smoking, Cholesterol
        Key modifiable factor in DR progression

 
Risk Factors for DR
 
  • Age
  • Type of diabetes
  • Renal disease
  • Pregnancy
  • Atherosclerotic disease
  • Medication

 
Duration of DM - Type 1
 
  • By 5 years, 25% have some DR

  • By 10 years, 60% have some DR

  • By 15 years, 80% have some DR

    • 25% have PDR at 15 years

 
Duration of DM - Type 2
 
  • By 5 years, there is some DR present in

    • 40% of patients on insulin
    • 24% of patients not taking insulin
    • 2% of patients have PDR

  • By 19 years, some DR is present in

    • 84% of patients on insulin
    • 53% of patients not taking insulin
    • 25% of patients have PDR

 
Clinical Signs

     
Clinical Signs
 

     

     

     

 
Classification

     
Background Diabetic Retinopathy
 

 
Severe Background Diabetic Retinopathy
 

 
Proliferative Diabetic Retinopathy
 

 
Diabetic Clinically Significant Diabetic Macular Oedema (CSME)
 

 
Treatment

     
Visual Impairment in DM
 
No visual impairment vs legal blindness in all diabetics diagnosed after age 30 years

Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR) 1980-1982

 
Visual Loss in DR
 
  • Primarily caused by complications of the microvascular abnormalities

      • Vitreous hemorrhage (VH)
      • Macular edema (CSME)
      • Tractional retinal detachment (TRD)
      • Neovascular glaucoma (NVG)
      • Macular ischemia

 
Detection & Prevention of DR
 
  • 90% of severe vision loss can be avoided with treatment1

  • In one study of 2000 patients2

      • 11% of type 1 with high-risk PDR had not been seen by an ophthalmologist in 2 years
      • 7% of type 2 with high-risk PDR also had not been seen in 2 years
      • 46% of eyes with high-risk PDR had not received laser photocoagulation
1. Ferris FL. JAMA 1993;269:1290-1
2. Klein R. et al., Ophthalmology 1987

 
Treatment of DR
 
  • Control BSL (HbA1c <8%), BP, cholesterol, weight etc

  • Get GP, Endocrinologist, Physicians involved

  • Ophthalmologist
      • Laser treatment
      • Intravitreal injections (steroids, anti-VEGF agents)
      • Surgery
      • Regular eye review for early detection of retinopathy

 
Focal Macular Laser of CSME
 

 
Panretinal Photocoagulation (PRP) for New Vessels (PDR)
 

 
Side Effects of Laser
 
  • Discomfort
  • Transient visual blur
  • Peripheral field loss
  • Glare sensitivity
  • Colour discrimination
  • Long term visual loss (from worsening maculopathy, foveal burn)

 
Intravitreal Steroids or Anti-VEGF
 
For macular oedema or neovascularisation

 
Vitrectomy Surgery
 
For vitreous haemorrhage, tractional retinal detachment or macular fibrosis

 
Conclusions
 
  • Strict control of BSL and other risks is imperative

  • Team approach with GP, endocrinologist, others

  • Early detection of any retinopathy through regular examination