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Glaucoma Drugs

Topic updated on 06/06/17 8:43pm

Snapshot
  • A 56-year-old man presents to the emergency department with severe eye pain, headache, blurry vision, and seeing halos around lights. His symptoms occured after he was in the movie theatre. Medical history is noncontributory. On physical examination, there is reduced visual acuity and a mid-dilated right pupil that is cloudy and poorly responsive to light. Intraocular pressure is 62 mmHg (normal is 8-20 mmHg.) The on call ophthalmologist is emergently consulted and in the meantime the patient is given timolol, apraclonidine, and pilocarpine drops that are administered one minute apart. (Angle-closure glaucoma)
Introduction
  • Glaucoma is an optic neuropathy leading to optic nerve head atrophy and is
    • typically associated with an elevated intraocular pressure
  • The goal of treatment is to decrease intraocular pressure
    • recall that aqueous humor production
      • begins in the nonpigmented epithelium of the ciliary body
        • α-agonists, β-blockers, and carbonic anhydrase inhibitors can act here
      • the aqueous humor then flows from the posterior chamber → anterior chamber → trabecular meshwork canal of Schlemm
        • the uveoscleral outflow can be influenced by
          • prostaglandin analogs
        • the trabecular outflow can be influenced by
          • cholinomimetics
 
Glaucoma Drugs
Medication
Mechanism of Action
Side Effects
α2-agonists
  • Brimonidine
    • ↓ aqueous humor production                                            
  • Allergic and follicular conjunctivitis
  • Contact dermatitis
  • Blurry vision
β-blockers
  • Timolol, betaxolol, and carteolol
    • ↓ aqueous humor production
  • No changes in pupil size or vision
Carbonic anhydrase inhibitor
  • Acetazolamide
    • ↓ aqueous humor production via inhibition of
      • carbonic anhydrase
  • No changes in pupil size or vision
Cholinomimetics
  • Pilocarpine and carbachol
    • ↑ aqueous humor outflow via
      • ciliary muscle contraction by
        • directly stimulating cholinergic receptors
  • Physostigmine and echothiopate
    • ↑ aqueous humor outflow via
      • ciliary muscle contraction by
        • indirectly stimulating cholinergic receptors
  • Miosis
  • Cyclospasm
Prostaglandins
  • Bimatoprost and latanoprost are PGF2α analogs that
    • ↑ aqueous humor outflow
  • Periocular hyperpigmentation
  • Increased and/or misdirected eyelash growth
 


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