Primary open-angle glaucoma Flashcards
What are glaucomas?
Glaucomas are optic neuropathies associated with raised intraocular pressure (IOP).
How are glaucomas classified?
They can be classified based on whether the peripheral iris is covering the trabecular meshwork.
What is primary open-angle glaucoma (POAG)?
In POAG, the iris is clear of the trabecular meshwork, leading to increased resistance to aqueous outflow and increased IOP.
What is the significance of raised IOP?
It is now recognised that a minority of patients with raised IOP do not have glaucoma and vice versa.
What are the risk factors for POAG?
Risk factors include increasing age, genetics, Afro Caribbean ethnicity, myopia, hypertension, diabetes mellitus, and corticosteroids.
How does age affect the risk of POAG?
POAG affects < 1.5% of individuals under 55 years of age but up to 10% over the age of 80 years.
What is the chance of first-degree relatives developing POAG?
First-degree relatives of an open-angle glaucoma patient have a 16% chance of developing the disease.
How may POAG present?
POAG may present insidiously and is often detected during routine optometry appointments.
What are the features of POAG?
Features may include peripheral visual field loss, decreased visual acuity, and optic disc cupping.
What are the fundoscopy signs of POAG?
- Optic disc cupping (cup-to-disc ratio >0.7)
- Optic disc pallor
- Bayonetting of vessels
- Additional features like cup notching and disc haemorrhages.
How is POAG diagnosed?
Diagnosis involves case finding and provisional diagnosis by an optometrist, followed by referral to an ophthalmologist.
What investigations are done for POAG?
Investigations include automated perimetry, slit lamp examination, applanation tonometry, central corneal thickness measurement, and gonioscopy.
What does automated perimetry assess?
Automated perimetry assesses the visual field.
What does applanation tonometry measure?
Applanation tonometry measures intraocular pressure (IOP).
What is the purpose of assessing risk factors in POAG?
Assessing risk factors helps evaluate the risk of future visual impairment.
What are glaucomas?
Glaucomas are optic neuropathies associated with raised intraocular pressure (IOP).
How are glaucomas classified?
They can be classified based on whether the peripheral iris is covering the trabecular meshwork.
What characterizes open-angle glaucoma?
In open-angle glaucoma, the iris is clear of the trabecular meshwork.
What is the aim of treatment for glaucoma?
The aim of treatment is to lower intraocular pressure to prevent progressive loss of visual field.
What does NICE recommend as first-line treatment for IOP ≥ 24 mmHg?
NICE guidelines offer 360° selective laser trabeculoplasty (SLT) as first-line treatment.
What are the benefits of 360° SLT?
360° SLT can delay the need for eye drops and can reduce but does not remove the chance they will be needed at all.
What is the next-line treatment after SLT?
Prostaglandin analogue (PGA) eyedrops should be used next-line.
What are the next lines of treatment after PGA eyedrops?
The next line includes beta-blocker eye drops, carbonic anhydrase inhibitor eye drops, and sympathomimetic eye drops.
When may surgery be considered in glaucoma management?
Surgery in the form of a trabeculectomy may be considered in refractory cases.
What is the mode of action of prostaglandin analogues?
Prostaglandin analogues (e.g. latanoprost) increase uveoscleral outflow.
What are the adverse effects of prostaglandin analogues?
Adverse effects include brown pigmentation of the iris and increased eyelash length.
What is the mode of action of beta-blockers?
Beta-blockers (e.g. timolol, betaxolol) reduce aqueous production.
Who should avoid beta-blockers?
Beta-blockers should be avoided in asthmatics and patients with heart block.
What is the mode of action of sympathomimetics?
Sympathomimetics (e.g. brimonidine) reduce aqueous production and increase outflow.
What should be avoided when taking sympathomimetics?
Avoid if taking MAOI or tricyclic antidepressants.
What are the adverse effects of sympathomimetics?
Adverse effects include hyperaemia.
What is the mode of action of carbonic anhydrase inhibitors?
Carbonic anhydrase inhibitors (e.g. Dorzolamide) reduce aqueous production.
What reactions may occur due to systemic absorption of carbonic anhydrase inhibitors?
Systemic absorption may cause sulphonamide-like reactions.
What is the mode of action of miotics?
Miotics (e.g. pilocarpine) increase uveoscleral outflow.
What are the adverse effects of miotics?
Adverse effects include a constricted pupil, headache, and blurred vision.
