Laser iridotomy vs lens removal

Lens removal is more effective in controlling intraocular pressure (IOP) in primary angle closure glaucoma than laser peripheral iridotomy (LPI) and LPI has limited benefit for preventing angle closure, according to recent studies. These and other findings suggest too many LPIs are being performed, said David S Friedman MD, MPH, PhD, Albert and Diane Kaneb professor and director of the glaucoma service at Massachusetts Eye and Ear, Harvard Ophthalmology, Boston, USA, at AAO Virtual 2020. Regarding LPI vs lens extraction for acute primary angle closure attacks, Dr Friedman cited two studies that found patients treated with phaco were more likely to control IOP without medications up to 80 weeks after the closure attack (Lam DS et al. Ophthalmology. 2008 Jul;115(7):1134-40) and 24 months after the attack (Husain et al. Ophthalmology. 2012 Nov;119(11):2274-81). Similarly, for chronic angle closure, the EAGLE trial, involving 419 eyes in the UK, Asia and Australia, reported that lens extraction was better than LPI at IOP control, requiring fewer medications at a mean of 0.4±0.8 v 1.3±1.0, and providing better patient-reported quality of life at 36 months. Early lens extraction was also likely to be cost-effective for treating patients with newly diagnosed primary angle closure (with intraocular pressure 30mmHg or higher) and primary angle closure glaucoma. On the downside, lens extraction runs a risk of posterior capsule rupture so treatment decision should consider individual risk factors, Dr Friedman said. The EAGLE results are also not generalisable to other types of primary angle closure or primary angle closure glaucoma (AzuaraBlanco et al. Lancet. 2016 Oct 1;388(10052):1389-1397). A study involving 889 patients in Guangzhou, China, with angle closure without disease and one eye randomised to LPI found that while LPI was protective in reducing peripheral anterior synechiae, overall rates of PAS of one clock hour or more as well as IOP over 24mmHg and acute angle closure attacks were very low in the population studied. Just two control eyes over six years suffered acute attacks outside of dilation (three attacks occurred with dilation), leading Dr Friedman to conclude that “we may be doing too many LPIs”. Adding iridoplasty to LPIs did not add value, another study found. In addition, a 2016 Cochrane review concluded that LPI is not effective for treating pigment dispersion, Dr Friedman noted.As for location of LPIs, studies are inconsistent as to whether a superior v nasal or temporal position causes more dysphotopsias, though one study found more linear disturbances with a superior position and more pain with a temporal position, Dr Friedman said. David S Friedman: friedman@meei.harvard.edu

Tags: lens removal angle closure glaucoma