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Editors Selection IGR 7-3
Surgical treatment: Cataract extraction and ACG
Comment by Paul Foster on:
12464 Cataract surgery for residual angle closure after peripheral laser iridotomy, Nonaka A; Kondo T; Kikuchi M et al., Ophthalmology, 2005; 112: 974-979
The retrospective study by Nonaka et al. (570) examines the role of lens extraction for cases of angle-closure where a laser peripheral iridotomy (PI) has been performed but angle-closure persisted on ultrasound biomicroscopy, and a dark-prone provocative test induced a rise in IOP < 5 mmHg. The study was retrospective, and reports on 70 eyes of either 39 or 40 Japanese patients (depending on the section of the paper one reads). The case-mix includes 16 people with narrow angles, 25 with either raised IOP and closed angles or peripheral anterior synechiae (PAS) and 29 with glaucomatous optic neuropathy attributable to angle-closure. Only 13 eyes of 9 people had residual angle-closure after laser iridotomy, and underwent 'cataract surgery'. An unspecified number underwent clear lens extraction when IOP was medically uncontrolled (definition unspecified). The case-mix of the 13 eye undergoing lens surgery is not stated. In the operated group, mean IOP fell from 19.3 to 14.8 mmHg, with a fall in mean number of medications (1.5 to 0.4). Other comparative data are incomplete, specifically those reporting IOP distribution before and after PI, and visual field defects (giving figures for between 48 and 58 of the 70 eyes). However, among those undergoing 'cataract' extractions, the drainage angle in all quadrants of all eyes became open after cataract surgery. This is somewhat surprising as it would either indicate that no PAS were present, or that PAS were divided during the surgery. It is an important omission that the amount of PAS in not described anywhere in the report, and will presumably give an indication of long-term prognosis.
It is not clear how the subjects were identified in this retrospective study, nor possible to judge how representative they were of all patients in the clinic. The fact that they were 'those who remained under follow-up' may indicate a more severe spectrum of disease. The conclusion that residual angle-closure was common after PI may therefore not be justified. This report raises as many questions as it answers. Specifically, the role of clear lens extraction for angle-closure suspects may represent a different balance of risk and benefit for the patient compared with those who have visually significant cataract. Many ophthalmologists would probably consider laser iridoplasty, or simply careful observation, to be the management of choice.
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