Angle- closure glaucoma Flashcards
What is a Glaucoma?
- A collection of disorders resulting in progressive optic neuropathy
- Raised intraocular pressure is a key factor
What is open-angle glaucoma?
- a normal angle between the iris and the cornea
- There are two forms primary and secondary
- Primary is the most common cause
- Some have normal pressure glaucoma
What is angle- closure glaucoma?
- Closing or narrowing of the angle between the iris and the cornea
- This is split into primary and secondary forms
- Primary is more common
- The closure of the anterior chamber angle results in reduced drainage of the aqueous humour and rising IOP
How common is Glaucoma?
- Affects 0.4% of those over the age of 40
What are the Risk Factors for Glaucoma?
- Women are 2/4 times more likely to be affects
- Age
- Ethnicity ( highest in people of Asian and Inuit heritage)
- Family history
- Hyperopia
- Anticholinergic topical drops ( pupil dilators)
- Systemic medications ( antimuscarinic or adrenergic medications)
What are the chambers of the eye?
- Anterior
- Posterior
- Vitreous
What is the anterior chamber of the eye?
- Located anteriorly between the cornea and iris
- Filled with aqueous humour that flows from the posterior chamber
What is the Posterior Chamber?
- located behind the anterior chamber, between the iris and the lens.
- This is where the aqueous humour is produced by the ciliary epithelium/bodies
What is the Vitreous Chamber?
- This is located behind the posterior chamber between the lens and the back of the eye
- This is filled with vitreous humour (fluid with a gel like consistency)
Explain the production of the Aqueous Humour?
- The aqueous humour is produced and actively secreted by the ciliary body and epithelium in the posterior chamber of the eye
- It is a watery fluid with a similar make-up to plasma, however it has a far lower protein content
Explain the drainage of the aqueous humour?
- The aqueous humour passes through the pupil into the anterior chamber of the eye
- It drains at the anterior chamber angle (iridocorneal angle)
- 2 drainage pathways:
1. Canal of Schlemm: the majority of aqueous humour drains via the trabecular meshwork into the canal of schlemm
2. Uveoscleral pathway: some of the aqueous humour may drain via the ciliary muscle into the supraciliary and suprachoroidal spaces
What is the Primary Pathophysiology for angle-closure glaucoma?
- primary = anatomical predisposition
- In primary angle-closure, the lens is located anteriorly and presses against the iris.
- This interrupts normal flow through the chambers with the pressure building in the posterior chamber behind the iris
- As the iris pushes forward it closes the anterior chamber angle
- Contact with the iris leads to scar tissue formation within the trabecular meshwork further reducing drainage
What are the three stages that primary angle-closure glaucoma can be split into?
- Acute
- Subacute
- Chronic
What is an acute angle closure glaucoma?
- Complete blockage of the anterior chamber angle resulting in a rapid rise in IOP.
- Results in acute symptoms of eye pain, vision loss, redness, headache and vomiting
- Ophthalmological emergency requiring urgent treatment!
What is a subacute angle-closed glaucoma?
- Closure of the angle results in acute symptom development but follows a self-limiting and recurrent pattern
What is a chronic angle-closed glaucoma?
- Incomplete closure or scarring reduces drainage of aqueous humour but does not cause as sudden and high rises in IOP
- It is often asymptomatic and be picked up incidentally or in advanced disease when vision loss is noted
What is the Pathophysiology of secondary angle-closure glaucoma?
- space occupying lesion (push the iris/ciliary body)
- neovascularisation of iris (pull the iris causing deformity)
What are the Clinical Features of Acute angle- closed Glaucoma?
- Severe Eye Pain
- Red eye
- Semi-dilated and fixed pupil
- Visual Loss
- Halos ( seeing circles around lights)
- Headache
- Nausea and Vomiting
What are the clinical features of chronic angle-closed glaucoma?
- Typically asymptomatic
- Picked up on routine ophthalmic examination
What investigations would you do angle-closed glaucoma?
- Tonometry: To allow Intraocular pressure to be measured. Normal is 8-21 mmHg.
- Gonioscopy: This allow the assessment of the anterior chamber and the internal drainage system - with a special lens you can see the drainage angle of the eye
- Ophthalmoscopy/ slit lamp (shows changes consistent with glaucoma such as cupping
What are normal pressures of the eye?
8-21 mmHg
What are high pressures in the eye indicative of acute angle-closed glaucoma?
> 30 mmHg
What is Opportunistic testing?
- There is no formal screening programme for glaucoma
- Elderly: free eye exams every 2 years from 60-70 and free every year after 70
- FHx: >40 with a first degree family member affected by glaucoma has free yearly eye exams.
- Ethnicity: those of African Heritage should have free eye exams after 40 with the increased risk of glaucoma
What is the medical management of Acute angle-closed glaucoma?
- Carbonic anhydrase inhibitors (topical -Brinzolamide, oral - Acetazolamide): cause a reduction in the secretions of the aqueous humour and therefore reduction in IOP
- Topical Beta-blockers (Timolol): lowers the production of aqueous humour
- Topical sympathomimetics (Brimonidine tartrate) : reduce IOP by lowering the production of aqueous humour and increasing uveoscleral outflow)
- Topical Pilocarpine: Causes pupillary constriction, thins the iris and pulls it away from the trabecular meshwork
- Hyperosmotic agents (mannitol): reduces IOP through the extraction of fluid from the aqueous humour
What is the surgical managment for Acute angle-closed glaucoma?
- Anterior Chamber Paracentesis (direct fluid removal)
What is the Definitive Managment for Acute angle-closed glaucoma?
- Laser Peripheral iridotomy which involves creating an opening in the iris
- This allows for equalisation of pressures between the anterior and posterior chamber
- This treatment is done in both eyes to reduce the risk
What is the treatment for chronic angle-closed glaucoma?
- laser peripheral iridotomy
What is the Prognosis for chronic closed-angle Glaucoma?
- 50% of the glaucoma related blindness in the world
- 40-80% will have an episode in the contralateral eye in the following 5-10 years
What medications can precipitate acute angle-closed glaucoma?
- Adrenergic medications such as noradrenalin
- Anticholingeric medications such as oxybutynin and solifenacin
- TCA’s such as amitriptyline
What is the intial management for a life-threatening causes of red eye - whilst waiting to be seen by an ophthalmologist?
- Lie patient on their back without a pillow
- Give Pilocarpine eye drops (2% for blue and 4% for brown eyes)
- Give Acetazolamide 500mg orally (carbonic anyhdrase inhibitor)
- Give analgesia and an antiemetic
