Glaucoma

Notes

## Basic introduction

  • Glaucomas are a group of eye disorders that are characterized by the relative increase in intraocular pressure (IOP) and progressive damage of the optic nerve and visual loss.
  • Glaucoma is the 2nd leading cause of blindness in the world after cataract.
  • The open-angle glaucoma accounts for 2/3 of blindness due to glaucoma.
  • Types of glaucoma include open-angle glaucoma, closed-angle glaucoma, and normal-tension glaucoma.
  • Open-angle glaucoma develops slowly over time and there is no pain.
  • Closed-angle glaucoma can present gradually or suddenly (10% of cases)
  • In open-angle glaucoma, there is a slow exit of aqueous humor through the trabecular meshwork.
  • In closed-angle glaucoma, the iris blocks the trabecular meshwork.
  • The Normal-tension glaucoma is a subset of open-angle glaucoma in which intraocular pressure is normal. It is usually asymptomatic.

## Pathogenesis

  • Elevated IOP causes damage to the axons of retinal ganglion cells by nerve compression or reduction of blood flow

## Statistics

  • In Kenya, glaucoma is associated with 25,000 cases of blindness.
  • Glaucoma is responsible for 12.3% of visual impairment
Symptoms

## Closed-angle glaucoma (acute phase)

  • Severe eye pain
  • Blurred vision
  • Very high intraocular pressure (>30 mmHg)
  • Mid-dilated pupil
  • Redness of the eye
  • Nausea
  • Seeing halos around lights
  • Vision loss (normally permanent

## Open-angle glaucoma

  • It is mostly asymptomatic
  • It has no acute phase
  • There is slow loss of visual field
  • There is increased cup-to-disc ratio
Diagnosis
  • Ophthalmoscopy
  • Tonometry (to measure ocular internal pressure)
  • Perimetry
  • Gonioscopy
  • Pachymetry
  • Nerve fiber analysis
Differential
  • Acute conjunctivitis
  • Corneal ulcer
  • Eye trauma
  • High myopia
  • Keratitis
  • Ocular hypertension
  • Pigmentary glaucoma
  • Glaucomatocyclitic crisis
Prevention
  • Early diagnosis and treatment is the primary measure to prevent disease progression.
Reference

1. Kenyan Ministry of Health. Clinical guidelines for management and referral of common conditions at levels 4-6. Hospitals. 2009; 3:259-261.http://apps.who.int/medicinedocs/documents/s21000en/s21000en.pdf

2. Ministry of Health, Kenya. Kenya Essential Medicine List (2016). http://publications.universalhealth2030.org/uploads/KEML-2016Final-1.pdf

3. Prevention of Blindness and Visual Impairment. http://www.who.int/blindness/causes/en/ Access. 13th January 2017

4. Prata Ts, Kanadani F, Simoes R, et al; Angle-closure Glaucoma: treatment. Rev Assoc Med Bras. 2014 Jul;60 (4):295-7.

Management

## Pharmacotherapy

  • Alpha2-adrenergic agonists (e.g. brimonidine)
  • Carbonic anhydrase inhibitors (e.g. IV acetazolamide)
  • Miotic agents (e.g. pilocarpine)
  • Prostaglandin analogs (e.g. latanoprost, bimatoprost and travoprost
  • Topical beta-adrenergic receptor antagonists (e.g. timolol, levobunolol, and betaxolol)
  • Steroids (prednisolone eye drops)

## Surgery

  • Canaloplasty
  • Trabeculectomy
  • Glaucoma drainage implants
  • Laser-assisted nonpenetrating deep sclerectomy
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