Trabecular meshwork physically blocked
Medical emergency
- Sudden increase in intraocular pressure
- Caused by blockage of the drainage angle in the eye
Causes/Factors
- Anatomical variance - people with narrow drainage angles in their eye are more predisposed
- Age and gender - more common in old age and females
- Hyperopia (farsightedness) - shallower anterior chamber making them more susceptible
- Cataracts - increased risk
- Medications:
- Adrenergic medications (e.g., noradrenaline)
- Anticholinergic medications (e.g., oxybutynin and solifenacin)
- Tricyclic antidepressants (e.g., amitriptyline), which have anticholinergic effects
- Pupil dilation - medications or conditions that can cause pupil dilation can contribute to the development of acute glaucoma. Eye dilating drops are therefore contra-indicated
Clinical Features
Short history of:
- Severely painful red eye
- Blurred vision - reduced acuity
- Halos around lights
- Associated headache nausea and vomiting
Investigations
Clinical examination:
- Red eye
- Hazy cornea
- Decreased visual acuity
- Mid-dilated pupil
- Fixed-size pupil
- Hard eyeball on gentle palpation
Management
Acute
- Lying the patient on their back without a pillow
- Pilocarpine eye drops (2% for blue and 4% for brown eyes) (constricts pupils)
- Acetazolamide 500 mg orally (reduction in aqueous humour)
- Analgesia and an antiemetic, if required
Secondary Care
- Pilocarpine eye drops
- Acetazolamide (oral or intravenous)
- Hyperosmotic agents (e.g., intravenous mannitol) increase the osmotic gradient between the blood and the eye
- Timolol is a beta blocker that reduces the production of aqueous humour
- Dorzolamide is a carbonic anhydrase inhibitor that reduces the production of aqueous humour
- Brimonidine is a sympathomimetics that reduces aqueous humour production and increases uveoscleral outflow
Laser iridotomy
- Definitive treatment
- Making a hole in the iris using a laser
- Allows the aqueous humour to follow directly from the posterior camber to anterior chamber
Complications/red Flags
- Irreversible loss of vision
DVLA Notification
Must inform the DVLA for the following:
- If affects both eyes for car drivers
- One eye for commercial drivers
- Legal responsibility