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The jury is out
A t first sight, using retinectomy for treating glaucoma seemed extreme, even when most of the eyes treated were legally blind. More than 20 years ago, Robert Machemer described performing retinotomy to relieve traction in two patients with retinal detachment complicated by proliferative vitreoretinopathy (PVR).1 At the time retinotomy was considered extreme and surgically the last resort. Several years elapsed before small case series began to appear in literature.2–5 By the time that the Silicone Oil Studies Report 5 was published in 1993, retinotomy was firmly established.6 The surprise was not only that gas and oil were equally effective, but that nearly one third of all patients in the study were treated with relieving retinotomy. One side effect of retinotomy was, of course, hypotony.7
The clearance of radioactive water from the vitreous in rabbit eyes was studied by Moseley et al in the early 1980s.8 Foulds and Damato made the observation that the retinal pigment epithelium was not necessary for retinal reattachment and that the bulk flow of water was sufficient to keep the retina apposed.9 It was Kirchhof, however, who went on to identify the neurosensory retina as the main barrier to water outflow in 1993.10 With the courage of his conviction, he went on to publish the use of retinotomy and retinectomy to lower intraocular pressure on the first nine patients in 1994.11 The latest report in this month’s issue of the BJO (p 1094) by Joussen et al demonstrated the safety and efficacy with a 5 year follow up.
Modifying wound healing has made important contributions to the success of glaucoma drainage surgery.12 Despite the use of antimetabolites, there are a number of patients with so called intractable glaucoma refractory to conventional surgical treatment. The retina, of course, does not heal in so far as defects do not close.11 Theoretically, rectinectomy should provide a predictable outflow. None the less, the results show hypotony in some patients but, more importantly, there was a significant complication rate in terms of retinal detachment and PVR. While the theory may be sound and the treatment valid, ultimately rectinectomy is complex surgery only achievable in relatively few hands. Cyclodiode treatment is readily available, easy to apply and perhaps associated with less frightening complications.13
Rectinectomy is complex surgery only achievable in relatively few hands
In the 1980s, there was a high prevalence of glaucoma among patients with retinal detachment and PVR treated with repeated vitrectomies and silicone oil.14 Since then, the number of glaucoma cases has fallen dramatically partly as a result of the use of high viscosity purified silicone oil,15 but partly also because of the increasing use of retinotomy and retinectomy. The recently finished British prospective trial of 5-FU and heparin for PVR showed that 53% of patients were treated with retinotomy and retinectomy (Charteris DG, The use of 5-FU and low molecular heparin as adjuvant to surgery for proliferative vitreoretinopathy: a prospective randomised control trial, 2003, in preparation). For patients with PVR at least, cutting the retina is more commonplace than extreme, often first line treatment rather than last resort. In that sense, we may all be using retinectomy for glaucoma. There is no doubt cutting the retina lowers the intraocular pressure. However, the jury is out on whether, in the long run, retinectomy is more controllable or “titratable” than cycloablation.
Note in Proof
The jury is out
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