Written by Dr David Wechsler, Ophthalmologist, November 2017
Less common than Open angle glaucoma, Angle closure can be far more serious.
Angle closure can be
The ‘angle’ of the eye is the space between the iris (coloured part) and cornea (clear outer part at the front). It is important for eye pressure because the trabecular meshwork (where fluid drains out of the eye) is in the angle.
If the angle closes or even just narrows, fluid can build up causing elevated eye pressure.
Elevated eye pressure damages the optic nerve. Glaucoma is optic nerve damage.
Acute angle closure causes a sudden very high pressure. Symptoms can be severe, and patients usually seek help from a doctor or optometrist. If the condition is promptly recognised and appropriate referrals made, urgent treatment can avoid permanent damage.
Chronic angle closure is usually asymptomatic. Elevated eye pressure can be detected by IOP measurement by an Optometrist or Ophthalmologist. All patients with an elevated eye pressure should have gonioscopy to make sure they do not have angle closure.
Gonioscopy is where a special lens is used to view the angle to see if it is open or closed. It is an important part of the eye examination to assess patients who may have glaucoma.
Anterior segment OCT is a scan that can image the angle structures. This can help illustrate if the angle is narrow, and document changes after interventions.
Image: Anterior segment OCT images of a patient with angle closure, before and after laser iridotomy.
UBM is a special type of ultrasound which can give detail of angle structures, particularly useful in special or unusual cases.
Image: UBM of a patient with ‘plateau iris syndrome’, a less common type of angle closure glaucoma.
As for patients with all types of glaucoma, visual field assessment and optic disc imaging are important for assessing the degree of damage to the optic nerve which has occurred from the high pressure.
Laser peripheral iridotomy (LPI) is the most important.
Laser iridoplasty (less commonly performed)
Lens extraction/IOL (cataract surgery) can be extremely useful for patients with angle closure, especially if there is also cataract present.
When people have cataract surgery the lens of the eye is removed and replaced with an artificial lens (IOL) which is thinner than the original. Because the lens sits just behind the iris, when the new thinner lens is in place the drainage angle opens up.
Trabeculectomy (glaucoma filtering surgery)
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