NHMRC Glaucoma Guidelines - ANZGIG

NHMRC GUIDELINES FOR THE SCREENING, PROGNOSIS, DIAGNOSIS, MANAGEMENT AND PREVENTION OF GLAUCOMA
Chapter 10 – Laser therapy and surgery
Evidence Statements
• Evidence supports using laser iridotomy with adjunctive pre-operative medication, as the treatment of
choice for patients with acute angle closure.
• Expert/consensus opinion suggests that in patients who experience acute angle closure in one eye, the
fellow eye is at high risk of future closure and therefore prophylactic iridotomy can be clinically indicated.
• Evidence strongly supports using medication to rapidly reduce intraocular pressure as a short-term
measure pre-operatively, in patients with acute angle closure glaucoma.
Patients with chronic angle closure and chronic angle closure glaucoma
For patients with chronic angle closure, peripheral iridotomy is usually performed to relieve
the pupillary block component and this usually halts the progression of synechial closure and
progressive IOP elevation. However between three and nine percent of primary angle closure
cases will progress to glaucoma within two years despite iridotomy (Nolan, Foster, Devereux et al
2000). Iridotomy is described as the intervention of choice (AAO 2005a) as miotics may aggravate
pupillary block due to anterior rotation of the ciliary body. There is evidence that for some patients,
laser interventions need to be repeated over time, and that they become less effective on repeated
administrations. When laser therapy does not successfully lower IOP, or if IOP begins to rise again,
the next course of action may be a filtering procedure.
Generally, only one laser iridotomy is required, as more than one iris hole has no greater effect on
pupil block. Usually a single hole will remain open indefinitely. However, in patients with uveitis,
the iris hole can close and may require re-opening.
point of note
After an iridotomy, between three and nine percent of primary angle closure cases will still progress
to glaucoma within two years. A greater number of patients will progress to glaucoma in a slower
manner, and retain occludable angles, or angles that re-narrow. Therefore post-iridotomy patients
need to be kept under regular review.
Laser iridoplasty: Following laser iridotomy, the angle may remain narrow with appositional contact
between the iris and trabecular meshwork, or open a little then re-narrow. The mechanisms include
large lens, ciliary block, and plateau iris amongst others. It will not work in synechial closure or most
other forms of secondary angle closure. Contraction laser burns applied to large areas of peripheral
iris will straighten peripherally curved iris and pull it away from the trabecular meshwork in some
cases. A recent publication, which was outside the scope of this literature review, highlighted the
paucity of literature concerning this therapy (Ng, Ang & Azzurro Blanco 2009).
Failure of laser therapy: Surgery should be considered when the angle closes further, in spite of
laser and medication treatment, and when the eye continues to demonstrate significant pressure
elevation or risk of acute angle closure. Patients with enlarged lens or ciliary block component
should have lens extraction performed prior to drainage surgery.
point of note
Expert opinion indicates that laser iridoplasty improves angle configuration in approximately half
the patients with chronic angle closure. The effect of laser frequently reduces over one to two
years. The treating health care provider must avoid over-treatment, as there is a risk of inducing iris
atrophy and permanent mydriasis.
National Health and Medical Research Council 145