Acute primary angle-closure glaucoma

An attack of acute primary angle closure glaucoma
occurs due to a sudden total angle closure leading to
severe rise in IOP. It usually does not terminate of its
own and thus if not treated lasts for many days. This
is sight threatening emergency.
Clinical features
Symptoms
Pain. Typically acute attack is characterised by
sudden onset of very severe pain in the eye
which radiates along the branches of 5th nerve.
Nausea, vomiting and prostrations are frequently
associated with pain.
Rapidly progressive impairment of vision,
redness, photophobia and lacrimation develop in
all cases.
Past history. About 5 percent patients give history
of typical previous intermittent attacks of subacute
angle-closure glaucoma.
Signs (Fig. 9.19)
Lids may be oedematous,
Conjunctiva is chemosed, and congested, (both
conjunctival and ciliary vessels are congested),
Cornea becomes oedematous and insensitive,
Anterior chamber is very shallow. Aqueous flare
or cells may be seen in anterior chamber ,
Angle of anterior chamber is completely closed
as seen on gonioscopy (shaffer grade 0),
Iris may be discoloured,
Pupil is semidilated, vertically oval and fixed. It
is non-reactive to both light and accommodation, IOP is markedly elevated, usually between 40 and
70 mm of Hg,
Optic disc is oedematous and hyperaemic,
Fellow eye shows shallow anterior chamber and
a narrow angle (latent angle closure glaucoma).
Clinical course of acute primary angle-closure
glaucoma.
The clinical status of the eye after an attack of acute
PACG with or without treatment is referred to post
congestive glaucoma (details are given below).
Diagnosis
Diagnosis of an attack of primary acute congestive
glaucoma is usually obvious from the clinical features.
However, a differential diagnosis may have to be
considered :
1. From other causes of acute red eye. Acute
congestive glaucoma sometimes needs
differentiation from other causes of inflammed
red eye like acute conjunctivitis and acute
iridocyclitis (see page 146-147).
2. From secondary acute congestive glaucomas
such as phacomorphic glaucoma, acute
neovascular glaucoma and glaucomatocyclitic
crisis.
Management
It is essentially surgical. However, medical therapy is
instituted as an emergency and temporary measure
before the eye is ready for operation.
(A) Medical therapy
1. Systemic hyperosmotic agent intravenous
mannitol (1 gm/kg body weight) should be given
initially to lower IOP.
2. Acetazolamide (a carbonic anhydrase inhibitor)
500 mg intravenous injection followed by 250 mg
tablet should be given 3 times a day.
3. Analgesics and anti-emetics as required.
4. Pilocarpine eyedrops should be started after the
IOP is bit lowered by hyperosomtic agents. At
higher pressureiris sphincter is ischaemic and
unresponsive to pilocarpine. Initially 2 percent
pilocarpine should be administered every 30
minutes for 1-2 hours and then 6 hourly.
5. Beta blocker eyedrops like 0.5 percent timolol
maleate or 0.5 percent betaxolol should also be
administered twice a day to reduce the IOP.6. Corticosteroid eyedrops like dexamethasone or
betamethasone should be administered 3-4 times
a day to reduce the inflammation.
(B) Surgical treatment
1. Peripheral iridotomy. It is indicated when
peripheral anterior synechiae are formed in less
than 50 percent of the angle of anterior chamber
and as prophylaxis in the other eye. Peripheral
iridotomy re-establishes communication between
posterior and anterior chamber, so it bypasses
the pupillary block and thus helps in control of
PACG. Its surgical technique is described on
page 237.
Laser iridotomy, a non-invasive procedure, is a
good alternative to surgical iridectomy.
2. Filtration surgery. It should be performed in
cases where IOP is not controlled with the best
medical therapy following an attack of acute
congestive glaucoma and also when peripheral
anterior synechiae are formed in more than 50
percent of the angle of the anterior chamber.
Mechanism: Filtration surgery provides an
alternative to the angle for drainage of aqueous
from anterior chamber into subconjunctival
space.For surgical technique, see page 238.
3. Clear lens extraction by phacoemulsification with
intraocular lens implantation by has recent been
recommended by some workers.
(C) Prophylactic treatment in the normal fellow eye
Prophylactic laser iridotomy (preferably) or surgical
peripheral iridectomy should be performed on the
fellow asymptomatic eye.