03Jun2011 from 26Jun2010 1640hrs presented at the COS Annual Meeting in Quebec City by Mr Paul Foster from Moorfields Eye Hospital (designation in the UK is such that Mr is the term for full consultant as opposed to Dr)
The diagnosis and management of ACG has been a relatively evidence free zone - “Small eye, big trouble.”
Primary vs secondary angle closure
The first step is to figure out if primary or secondary ACG; therefore you have to perform gonioscopy. Another test to help differentiate between primary and secondary is the use of biometry. The biometry tends to be symmetrical in the primary angle closure. Secondary tends to be in normal or big eyes and more asymmetrical. There is a large list of secondary ACG - iatrogenic, uveitis, NVG and many more
Laser iridotomy treatment
Laser iridotomy is still standard management, at or near 12:00 between 50-200 ums (though some advocate temporal placement to minimize light streaks.) Dark irides harder to get through so consider initial argon then complete with a YAG [editorial note: but bear in mind that with argon use also comes increased risk of inflammation.]
Apraclonidine and oral agents are used as pre-treatment at Moorfields’ Eye Hospital. Argon pre-Tx in most Asians and Africans as a confluent rosette at 100 mW then raise energy to 750 mW to create crater. Complications include a white horizontal/dark vertical line and about 1% rate visual disturbances such as glare, as well as transient bleeding and blurring.
Looking at response to LPI in China by using UBM before and after and identified the following risks for LPI failure:
- narrower angle
- more anterior positioned Ciliary Body
- thicker iris
- more anterior iris insertion
Role of laser iridoplasty
Laser iridoplasty is worth considering if still closed after LPI. It produces a fair amount of inflammation lasting for up to a couple of weeks. Basically avoid iridoplasty if established PAS but it can be done early on in acute ACG (a study in Hong Kong showed good response in first hour more so than medical treatment.)
What if LPI and/or iridoplasty not enough?
What med to use if LPI not enough? Prostaglandin Analogs seem to work very well. Trabeculectomy should NOT be done in acute case; study found too high a complication rate.
Wendy Franks at Moorfields’ offers the following advice:
- only do a trab in eye with ACG if have a gun to your head
- never to trab in phakic nanophthalmic eye even if have gun to your head
- if you do, you will get a gun to your head
Phacoemulsification cataract extraction may be a better surgical option for the treatment AACG.
“Salmon’s triad” for good prognosis:
- presenting IOP
- extent of PAS
- presence of GON
Other thoughts before doing cataract surgery on these patients:
Consider and exclude secondary causes; assess Visual Function both eyes; and do Biometry (if axial length <21, check scleral thickness
Impact of lens extraction on IOP in ACG, generally good trend toward improvement in study that speaker was involved with
Did best if higher pre-op IOP, greater number pre-op meds, narrower angle, greater degree PAS, etc
In small eyes use long tunnels and cohesive viscoelastics, don’t piggy back lenses
Started EAGLE study looking at Effectiveness of Angle closure Glaucoma Lens Extraction and hope to have results in a few years
Bottom line if iridotomy and meds fail, do not do trab, instead do Phaco IOL