Peripheral iridectomy in angle-closure glaucoma: A common complication

Abstract

Of 63 eyes which had prophylactic peripheral iridectomy, 21 (33 per cent.) developed posterior pupillary synechiae. They had been treated post-operatively with gutt. atropine 1 per cent. or (in two cases) with homatropine 1 per cent. The sector of the pupil related to the iridectomy quadrant was affected more often than chance would suggest, but all four quadrants were also affected in a rather high proportion of cases. The breadth of the peripheral iridectomy was significantly greater in eyes which developed synecbiae in the iridectomy quadrant alone than in eyes which failed to develop synechiae. The pupil had a D shape in the undilated and the dilated state. The average fall in the best corrected visual acuity of the eyes which did not develop synechiae was 1 line on Snellen's test chart, whereas that of eyes which did develop synechiae was 2 -05 lines; although this difference was not statistically significant, the variances of the two groups did differ significantly. The causes suggested, in order of importance, are: (a) Ineffectiveness of atropine as a preventer of synechiae; (b) Relative unresponsiveness to atropine of the iridectomy quadrant, especially when (c) The peripheral iridectomy is broad; (d) Unresponsiveness to atropine of the whole iris (especially in eyes with all four quadrants affected by pupillary synechiae), either because of an inherent property common in elderly patients or because of a marked inflammatory reaction. Other factors are: (e) Absence of a flow of aqueous through the pupil because of the peripheral iridectomy; (f) A wide area of iris in contact with the lens for the same reason, and also probably (g) Firm application of the iris to the lens because of the shallow anterior chamber. (h) Localized inflammation in ? necrotic area of iris between pupil and iridectomy. For clinical purposes, in order to minimize the danger of posterior synechiae, we aim to do a peripheral iridectomy which is small in all dimensions (although the particular measurements we actually made justify a narrow rather than a broad one), we prescribe gutt. phenylephrine 10 per cent. twice daily (recommending that the pupil should be seen to dilate in all sectors on this treatment), and also topical corticosteroids which should minimize traumatic iridocyclitis.