Download Glaucomas

Glaucomas
Consider the preservative in eye drops as some,
especially benzalkonium chloride, can irritate and
damage the cornea and may cause symptoms
similar to those of dry eye syndrome. These may
improve after swapping to less irritant or
preservative-free products. See also Preservatives
p 461.
Acetazolamide may be used if topical treatment,
laser or surgical interventions are not possible or
have poor outcomes.
See also www.nhmrc.gov.au/guidelines/publications/
cp113-cp113b
Glaucomas are characterised by optic neuropathy,
optic disc changes and irreversible, progressive
visual field loss. They are primarily classified as
either open-angle or angle-closure.
Open-angle glaucoma
Increased intraocular pressure (IOP) or ocular
hypertension (although not a defining characteristic) is the only modifiable risk factor for glaucoma. Though not all people with raised IOP will
develop glaucoma, it is more likely in those with
major risk factors, such as older age, strong family
history. Early treatment preserves the visual field
and reduces rate of glaucoma progression whether
or not IOP is raised.
A target IOP for treatment is determined based
upon the patient’s risk factors for glaucoma
progression, the amount of initial damage and the
rate of deterioration.
Laser or surgical interventions are considered if
drug treatment is inadequate or intolerable.
Practice points
• assess treatment by monitoring changes in visual
field and optic disc appearance
• a leaflet on eye drop administration is available
from Glaucoma Australia at www.glaucoma.org.au/
eyedrops.htm (see also Counselling p 461)
Angle-closure glaucoma
Up to 75% of patients with angle-closure glaucoma
will have intermittent or chronic angle closure with
asymptomatic progressive loss of visual field
rather than an acute crisis. Initial treatment is
iridotomy (laser or surgical); if unsuccessful,
surgical procedures are considered. Topical
treatment may be used, particularly in those with
persistent raised IOP despite laser or surgical
procedures.
Rationale for drug use
Prevent progressive loss of vision by lowering IOP.
Drug choice
See also Table 11–1 Comparison of topical drugs for
open-angle glaucoma p 461
Risk factors for angle-closure glaucoma
Risk factors include Asian ethnicity, small eye,
narrow angle of anterior chamber, shallow anterior
chamber, long sight, age and female gender. Use of
some drugs may precipitate acute angle-closure
crisis.
Topical drugs are first-line treatment (either alone
or in combination). They reduce IOP by decreasing
production of aqueous humour and/or by increasing its outflow.
Consider starting, changing or adding medications
to just one eye, using the other as a control; assess
IOP within 2–4 weeks before treating the other eye.
Since glaucoma is usually asymptomatic, compliance is a major problem (up to 50% of patients fail
to use their medication correctly); check compliance when considering changing dose or adding a
new agent to an existing regimen.
Acute angle-closure crisis
This is a rare ophthalmic emergency: treatment is
by laser iridotomy. Oral, IV and topical medication
may be necessary to stabilise the eye and lower IOP
before laser iridotomy. IV acetazolamide, topical
pilocarpine, a topical beta-blocker, IV mannitol or
oral glycerol may be used; seek specialist advice.
Table 11–1 Comparison of topical drugs for open-angle glaucoma
Class
Doses per day Comments
prostaglandin analogues (bimatoprost,
latanoprost, tafluprost, travoprost)
1
•
•
•
•
first line
increase aqueous outflow
the most effective class
may cause iris hyperpigmentation and eyelash changes
beta-blockers (betaxolol, timolol)
1–2
•
•
•
•
first line
decrease aqueous production
may cause systemic adverse effects, eg bradycardia
generally avoided in severe or poorly controlled asthma
alpha2 agonists (apraclonidine,
brimonidine)
2–3
• second line
• increase aqueous outflow and decrease its production
• apraclonidine can only be used short term
carbonic anhydrase inhibitors
(brinzolamide, dorzolamide)
2–3
• second line
• decrease aqueous production
cholinergic (pilocarpine)
3–4
• rarely used (eg angle-closure glaucoma and some secondary
glaucomas), seek specialist advice
• increases aqueous outflow
• high incidence of adverse effects, eg blurred vision, headache
AMH © 2014
www.amh.net.au