Glaucoma

Glaucoma describes a range of disorders with a characteristic type of optic disc damage usually due to raised intraocular pressure.

Upper limit of normal intraocular pressure is 21mmHg

2 main divisions of glaucoma are: 
  • Open angle = chronic 
  • Closed angle = acute 


Open angle glaucoma 

Primary open angle glaucoma occurs in 1-2% of over 40s and over 4% of over 80s 

Patients are often asymptomatic visual losses tend to occur late in the course of the disease and is often peripheral

Fundoscopy may reveal optic disc cupping

  • Major risk factors 
    • FH in a first degree relative 
    • Myopia 
    • Advanced age
    • Afro-caribean origin 
    • Raised intra-occular pressure 
  • Other risk factors 
    • Diabetes 
    • Hypertension 
    • Hypothyroidism 
    • Steroid use 
    • Migraine 
    • Sleep apnoea 

Patients of afro-caribbean origin are at higher risk of progression to blindness 

Management 
  • Medical 
    • Eye drops 
      • First line: prostaglandin analogues (increase aqueous outflow from eye through the uveoscleral pathway) or beta blockers (reduce secretion of aqueous) 
      • Second line: carbonic anhydrase inhibitors and alpha agonists 
    • Oral medication: carbonic anhydrase inhibitors (reduce secretion of aqueous) 
  • Surgical 
    • Argon laser trabeculoplasty 
    • Trabeculectomy 


Closed angle glaucoma 

Closed angle glaucoma is a sight-threatening ophthalmic emergency characterized by a rapid rise in intraocular pressure as a result of obstruction of aqueous humour drainage from the anterior chamber of the eye. 

Presentation 
  • Painful red eye 
  • Semi-dilated, non-reactive pupil 
  • Periocular headache 
  • Halos around light
  • Loss of vision 
  • Nausea and vomiting 
  • Systemically unwell 
  • Affected eye is tender and feels hard to the touch

Risk factors for closed angle glaucoma include: 
  • Advanced age 
  • Female gender 
  • Far eastern origin 
  • Hypermetropia 
  • Medications (due to their pupil-dilating effects) 
    • SSRIs 
    • TCA 
    • Anticholingergics 

Treatment 
  • Acetazolamide IV
  • Pilocarpine 4% eye drops 
  • Laser iridotomy or iridoplasty 
  • Iridectomy if laser treatment fails 

Small print gem: carbonic anhydrase drugs are strucurally similar to sulfonamides so should be avoided if patients have an allergy to these 



References 

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