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Updated: Dec 15 2021

Glaucoma

Images
https://upload.medbullets.com/topic/120507/images/aqueous humor pathway - update - moises dominguez.jpg
  • Overview
  • Snapshot
    • A 46-year-old African American male presents for an opthalmic examination. Medical history is significant for hypertension and type II diabetes mellitus. On slit-lamp examination, there is cupping of the optic disc, with a cup-to-disc ratio > 0.6. Tonometry reveals intraocular pressure of 45 mmHg (normal is 8-21 mmHg). Peripheral field vision loss is noted on visual field exam.
  • Introduction
    • Optic neuropathy characterized by optic nerve damage and visual abnormalities
      • majority of patients have increased intraocular pressure (IOP)
        • important causative risk factor
        • associated with increased resistance to aqueous outflow
        • compresses retinal blood supply or retinal ganglion cells
          • optic disc atrophy with cupping → visual loss
            • increased cup-to-disc ratio
    • Glaucoma can be characterized into
      • open-angle or angle-closure
  • Epidemiology
    • a leading cause of blindness
    • open-angle glaucoma is more common
    • risk factor examples
      • family history
      • age
      • race
  • Presentation
    • Symptoms
      • open-angle
        • usually asymptomatic
        • insidious onset of peripheral vision loss
      • angle-closure
        • acute onset of blurry vision
        • painful
        • halos around lights
        • ↓ vision (photophobia/blurry vision)
    • Physical exam
      • open angle
        • no distinct physical exam findings
      • angle closure
        • fixed-dilated pupil
        • corneal clouding/edema
        • conjunctival injection/redness
        • eyeball firm to palpation
  • Evaluation
    • Measure IOP with tonometry
      • normal is 8-21 mmHg
    • Assessment of optic disc shows enlarged cup-to-disc ratio (> 0.4)
    • Visual field testing
    • Pachymetry
      • measures corneal thickness
        • if corneas are thick, it may falsely elevate IOP on tonometry
    • Gonioscopy
      • gold standard for angle-closure glaucoma
  • Differential
    • Macular degeneration
    • Ischemic optic neuropathy
  • Treatment
    • Open-angle
      • pharmacologic
        • increases aqueous outflow
          • prostaglandins (becoming first-line)
          • α-agonists
          • cholinomimetics
        • decreases aqueous production
          • carbonic anhydrase inhibitors
          • α-agonists
          • β-blockers
      • laser therapy
        • trabeculoplasty
      • surgical
        • filtration bleb
    • Angle-closure
      • iridotomy
        • definitive treatment, but not used for initial management
      • topical β-blockers and α2-agonists
        • epinephrine contraindicated!!!
          • α1-agonism causes mydriasis
      • oral carboanhydrase inhibitors (acetazolamide)
        • IV if patient has nausea/vomiting
  • Prognosis, Prevention, and Complications
    • Open-angle
      • prognosis
        • does not substantially reverse
      • prevention
        • may involve lowering IOP
      • complications
        • blindness
    • Angle-closure
      • prognosis
        • progressive vision loss that may lead to blindness
          • if not detected early and not properly managed
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