In my view, iridoplasty is a simple and effective means of opening an appositionally closed angle in acute angle closure, or for persistent appositional angle closure after elimination of pupillary block by iridotomy. However, iridoplasty was never developed nor intended to treat glaucoma per se. It is intended to be used to open an appositionally closed angle, to avoid acute or chronic angle closure and development or progression of peripheral anterior synechiae (PAS). It’s treating an anatomic condition – so this is what I will address.
Firstly, despite a couple of papers in the literature that state otherwise, argon laser peripheral iridoplasty (ALPI) will not break PAS. Also, you have to apply the burns truly peripherally – if you apply them in the mid-peripheral iris you won’t get the angle open. Use long, slow contraction burns, and go very peripherally. The iris stroma will contract toward the site of the burn, thinning out the iris, compacting it and opening the angle. If we look at 23 eyes with chronic appositional closure to the upper trabecular meshwork which were treated with iridoplasty in the 1980s, the angles of 20 eyes remained open for the entire follow up period of over six years, and three eyes needed a second treatment years later (1). When we compared our success rate in patients with chronic angle closure glaucoma with those of the Singapore National Eye Centre, we saw that most patients required further treatment after iridotomy to control IOP (2). Fifty-three percent of the eyes in Singapore went on to have surgery, as opposed to 31 percent in New York, and that’s because seven eyes in New York were controlled with iridoplasty – which was not used in the Singapore patients. We concluded that iridoplasty can help to avoid surgical intervention after iridotomy in eyes with chronic angle closure, glaucoma, elevated pressure and PAS, when there is some degree of appositional closure.
I started studying angle closure almost 40 years ago, after watching patients get treated with drops and acetazolamide and hyperosmotics for three days and turned into pretzels. We tried giving medication for one to two hours, then went on to iridoplasty, and had virtually 100 percent success. Then in the late 1990s, the groups at CUHK started doing iridoplasty without any medication at all (3). It works – you get an immediate pressure drop, and we now perform and advocate this method. One criticism I’ve heard is that there are no randomized trials of iridoplasty. But in my experience, this complaint is usually made by people who have never performed it. There were a lot of studies in the 1960s and 1970s, primarily in the British literature, that demonstrate the serious consequences of leaving appositionally closed angles untreated. It can lead to PAS, acute angle closure, and chronic glaucoma. So knowing that chronic appositional closure is harmful and leads to these adverse outcomes, I feel it would be neither justified nor ethical to withhold a therapy which has been shown to immediately open an appositionally closed angle, dramatically lower IOP, and potentially maintain the open angle for years to come.
References
- R Ritch et al., “Long-term success of argon laser peripheral iridoplasty in the management of plateau iris syndrome”, Ophthalmology, 111, 104–108 (2004). PMID: 14711720. M Rosman et al., “Chronic angle-closure with glaucomatous damage: long-term clinical course in a North American population and comparison with an Asian population”, Ophthalmology, 109, 2227–2231 (2002). PMID: 12466163. DS Lam et al., “Immediate argon laser peripheral iridoplasty as treatment for acute attack of primary angle-closure glaucoma: a preliminary study”, Ophthalmology, 105, 2231–2236 (1998). PMID: 9855152.
