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Retinopathy, Diabetic

BASICS

  • Definition: Most patients with diabetes mellitus (DM) develop diabetic retinopathy (DR), the leading cause of new cases of legal blindness (age 20–64).
  • Stages:
  • Nonproliferative diabetic retinopathy (NPDR)
  • Severe NPDR (preproliferative)
  • Proliferative diabetic retinopathy (PDR)

Pregnancy: May exacerbate DR.

EPIDEMIOLOGY

  • Incidence:
  • T1DM peak: 12–15 years
  • T2DM peak: 50–70 years
  • Prevalence:
  • Worldwide: 1/3 of DM patients
  • T1DM: 2/3 develop PDR, 1/3 DME (≥35 years DM)
  • T2DM: Reverse proportions

ETIOLOGY & PATHOPHYSIOLOGY

  • Microaneurysms, microvascular abnormalities
  • Retinal hypoxia → ↑VEGF → neovascularization (NV) and DME

RISK FACTORS

  • Renal disease
  • Hypertension
  • Smoking
  • Elevated lipids

PREVENTION

  • Optimize blood glucose control
  • Annual ophthalmologic exams

ASSOCIATED CONDITIONS

  • Glaucoma
  • Cataracts
  • Retinal detachment, vitreous hemorrhage
  • Diabetic papillopathy (disc edema)

DIAGNOSIS

Exam Findings

  • NPDR (background): microaneurysms, intraretinal hemorrhage, lipid deposits
  • Severe NPDR: cotton wool spots, venous beading/dilatation, IRMA, extensive hemorrhage
    ETDRS 4:2:1 rule:
    • Severe hemorrhages/microaneurysms (4 quadrants)
    • Venous beading (2+ quadrants)
    • IRMA (1+ quadrant)
  • PDR: NV on retina/optic nerve/iris; VH or traction RD

Differential Diagnosis

  • Radiation retinopathy, retinal vein occlusion, hypertensive retinopathy

Diagnostic Testing

  • Fluorescein angiography: Retinal nonperfusion, leakage, PDR
  • OCT: Detects/measures DME
  • OCT angiography (OCTA/SS-OCTA): Visualizes NV

TREATMENT

General Measures

  • Intensive glucose and blood pressure control slows progression (DCCT, UKPDS)
  • Avoid persistent hyperglycemia (≥200 mg/dL)
  • Address OSA if present (CPAP may help refractory DME)
  • Cataract surgery may worsen DR and increase DME risk

Medications

  • HTN: ARB (candesartan) may regress DR
  • Statins: Lower risk of DR and DME in T2DM

Procedures

DME

  • First-line: Intravitreal anti-VEGF (ranibizumab, aflibercept, bevacizumab [off-label], brolucizumab, faricimab)
  • Ranibizumab/aflibercept: monthly then extend interval
  • Bevacizumab: off-label
  • Faricimab: dual Ang2/VEGF inhibition, flexible interval
  • Brolucizumab: caution—vasculitis/occlusion risk
  • Laser: For persistent or non-center-involved DME
  • Steroid implants: Dexamethasone, fluocinolone (cataract, glaucoma risk)
  • Vitrectomy: For persistent DME with vitreomacular traction

NPDR/PDR

  • Severe NPDR (no CI-DME): Prophylactic aflibercept reduces progression, but no vision benefit over observation plus rescue therapy
  • PRP: Mainstay for PDR, reduces risk of severe vision loss
  • Anti-VEGF: Alternative or adjunct to PRP
  • Vitrectomy: For non-clearing VH, severe PDR, traction RD involving macula

Special Points

  • Topical povidone-iodine prophylaxis before IVI
  • IRI for DME improves DR severity, reduces progression risk
  • Observation may be appropriate for CI-DME with good VA

ONGOING CARE

  • Follow-up:
  • No retinopathy: yearly
  • Background DR: every 6 months
  • Pre-PDR: every 3–4 months
  • Active PDR: every 2–3 months
  • DME: every 4–6 weeks

DIET

  • Omega-3 intake: ≥500 mg/day (e.g., 2 servings oily fish/week) lowers DR risk in T2DM

PATIENT EDUCATION

  • Importance of regular eye exams
  • Tight glucose and BP control

PROGNOSIS

  • Good if detected and treated early
  • Delayed treatment → risk of blindness

COMPLICATIONS

  • Blindness
  • Vitreous hemorrhage
  • Traction retinal detachment
  • Sustained intraocular pressure elevation after repeated anti-VEGF

ICD-10 CODES

  • E11.319: T2DM w/o specified DR, w/o macular edema
  • E10.319: T1DM w/o specified DR, w/o macular edema
  • E10.329: T1DM w/ mild NPDR, w/o macular edema

CLINICAL PEARLS

  • Schedule yearly eye exams for all DM patients
  • DME: treat with focal laser, anti-VEGF, steroids, or vitrectomy (case dependent)
  • PRP for PDR; anti-VEGF is a valid alternative