Glaucoma Pharmacological Management

INTRODUCTION :
  • Glaucoma refers to a group of diseases characterized by
  • Optic neuropathy
  • Specific pattern of visual field defect
  • Raised IOP
MECHANISMS OF ACTION OF ANTI GLAUCOMA AGENTS:
  • Chief therapeutic measure is to lower IOP to the target level either by
  • Reducing aqueous production in the ciliary body
  • Promoting aqueous humour outflow through the trabecular meshwork
  • Promoting aqueous humour outflow via the uveoscleral pathway
CLASSIFICATION OF ANTI GLAUCOMA DRUGS:
  • Topical Drops
Beta blockers
  • e.g. timolol, carteolol, betaxolol,levobunolol and metipranolol
Adrenergic agonists
  • e.g. epinephrine, dipivefrin, brimonidine and apraclonidine
Prostaglandin analogue
  • e.g. latanoprost, bimatoprost ,unoprostone
Cholinergic agents
  • e.g. pilocarpine, carbachol,demecarium bromide and echothiophate iodide
Carbonic anhydrase inhibitors
  • e.g. dorzolamide and brinzolamide
  • Systemic Drops
Carbonic anhydrase inhibitors
  • e.g. acetazolamide and methazolamide
Osmotic agents
  • e.g. glycerine, mannitol and urea
BETA BLOCKERS:
  • First drug of choice for POAG
  • Lower IOP by reducing aqueous secretion due to their effect on β2 receptors
  • Topical β-blockers reduce aqueous formation by 24% to 48% in awake humans
  • β-blockers are ineffective during sleep
Mechanism of action:
  • By Antagonizing the effect of catecholamines it causes Reduction in aqueous secretion


Indications:
  • Open angle Glaucoma(DOC Timilol)
  • Angle closure Glaucoma
  • Secondary Glaucoma
  • Glaucoma in children
Contraindications:
  • Bronchial asthma
  • History of bronchial asthma
  • Severe COPD
  • Bradycardia 
  • Severe heart block
  • Overt cardiac failure
  • Children & infants
Advantages of topical n-blockers (timolol) over miotics (pilocarpine)
  • No change in pupil size (no miosis) → No fluctuation in I.O.T.
  • No induced myopia → Convenient once/twice daily applications
  • No ciliary spasm (no spasm of accomodation) → Few systemic side effects.
ADRENERGIC AGONIST :
  • Alpha 1 vasoconstriction of ciliary vessles decreased acqueous formation
  • Alpha 2 ciliary epithelium : decreased secretory activity
  • Mode of action
  • Decreasing aqueous formation by constricting the ciliary blood vessels
  • Increasing uveoscleral outflow by an increase in prostaglandin synthesis
Exam Question
  • Besides its properties of decreasing intraocular pressure, timolol is preferred in the treatment of glaucoma because it Produces no miosis
  • Drug of choice for open angle glaucoma Timolol

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