DIABETIC RETINOPATHY


Screening--see "Management of Type 2 Diabetes"

I. Epidemiology & natural history

  1. Prevalence in patients with type 1 DM is 25% at 5y, 60% at 10y, and 80% at 15y
  2. Risk is correlated with degree and duration of hyperglycemia, and to a lesser degree, with hypertension
  3. Risk of blindness greater for African-Americans than for whites with type 2 DM
  4. Progression can be accelerated by pregnancy, puberty, and cataract surgery
  5. Vision loss can result from macular edema or capillary nonperfusion (central vision loss), distortion and detachment of retina by new blood vessels and contraction of accompanying fibrous tissue, or hemorrhage in preretinal or vitreous spaces.

II. Nonproliferative form (earlier stage)

  1. Characterized by retinal microaneurysms, hemorrhages, and "cotton wool spots" (which represent small infarcts of retinal nerve fibers)
  2. Can also see retinal edema and "hard exudates" (lipid deposits) resulting from increased vascular permeability)
  3. In later, "preproliferative" stage, can get retinal vessel occlusion leading to retinal ischemia
  4. Usually not associated with vision impairment, though macular edema can occur and lead to vision loss

III. Proliferative form (later stage)

  1. New vessel formation (neovascularization) of disk or posterior pole; eventually vitreous hemorrhage, secondary retinal detachment, and visual loss
  2. Photocoagulation (by argon laser or xenon arc light) prevents further visual loss and may improve vision for some
  3. Vitrectomy is helpful if have vitreous hemorrhage, scarring, or retinal detachment

IV. Prevention

  1. Good glycemic control
  2. Addition of fibrate therapy to baseline statin therapy was associated with a RR 0.6 for new-onset retinopathy in the "ACCORD" trial

V. Management

  1. Laser photocoagulation reduces risk of vision loss; may be ass'd with risk of modest loss of visual acuity and contraction of visual field; usually recc'd only for pts with proliferative DM retinopathy or severe non-proliferative DM retinopathy
  2. Other treatments for advanced diabetic retinopathy:
    1. Virectomy
    2. Intravitreal glucocorticoids
    3. Vascular endothelial growth factor inhibitors, e.g. bevacizumab (Avastin)
  3. In proliferative or moderate-to-severe nonproliferative retinopathy, should avoid highly strenuous activity involving straining/Valsalva, which may precipitate vitreous hemorrhage or retinal detachment
  4. See other notes about management above
(Sources include Core Content Review of Family Medicine, 2012)