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Chronic narrow angle glaucoma (CNAG) occurs when the anterior chamber drainage angle progressively narrows with a subsequent rise in intraocular pressure (IOP) and, if this rise is maintained, glaucomatous optic neuropathy. Although there may be a number of reasons for this narrowing, if the peripheral iris remains apposed to the trabecular meshwork for any length of time it is likely that a more permanent adhesion occurs (PAS). Thus even though the underlying cause for the narrowing is removed—for example, pupillary block after peripheral iridectomy (PI) or cataract extraction in lens induced disease, the angle remains closed and the IOP remains damagingly high.
We have previously described a technique for use in acute angle closure glaucoma where the lens induced narrowing is removed by cataract extraction and the PAS broken with viscoelastic. This manoeuvre has been called viscogonioplasty (or VGP).1 This case series describes the results of this same technique in patients with chronic narrow angle glaucoma
From April 2002 to March 2005 all patients with CNAG inadequately controlled on conventional therapy were enrolled. The inclusion criteria were as follows:
Occludable angle confirmed by gonioscopy
Evidence of uncontrolled IOP (raised IOP, progressive glaucomatous optic neuropathy, and/or visual field progression)
Previous patent PI.
An occludable angle was defined as the angle in which the posterior (usually pigmented) trabecular meshwork was seen for less than 90° of the angle circumference.2
Exclusion criteria included:
Plateau iris syndrome
Previous glaucoma surgery (argon laser trabeculoplasty/trabeculectomy)
History of ocular injury
The duration of increased IOP or synechial angle closure was not one of our inclusion or exclusion criteria. However, all patients …