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Lens extraction in primary angle closure

Role debated over many years

The crystalline lens has a pivotal role in primary angle closure (PAC), both in the pathogenesis of pupil block1 and by exacerbating the effect of non-pupil block mechanisms such as peripheral iris crowding. Eyes with angle closure tend to have shallow anterior chambers and thick, anteriorly positioned lenses when compared with normal eyes.2–5 Removing the lens creates more space in the anterior chamber and widens the angle, which may be enough to achieve intraocular pressure (IOP) control.6 The role of lens extraction as a treatment for angle closure has been debated for many years. But with the knowledge that the lens is the single most important contributing factor to the angle closure process, and having acquired the technology and skills to perform relatively safe small incision cataract surgery, should we now be thinking about performing early lens extraction in angle closure patients with the aim of preventing the development of glaucomatous optic neuropathy at a later stage?

In this issue of the BJO (p 14) Tan and co-authors highlight some of the controversies and ethical considerations surrounding the role of early lens extraction in patients with acute angle closure. Theoretically, removing the lens at an early stage will deepen the anterior chamber and open the angle, thus hindering the formation of peripheral anterior synechiae (PAS) and improving the prospects for good long term IOP control. In addition, many of these patients will eventually require surgery for visually significant cataract at some stage.7 Tan et al report the corrected visual acuity of patients presenting with acute …