Mixed glaucoma.

Abstract

SUMMARY Two hundred and sixty-seven eyes which underwent peripheral iridectomy for presumed angle-closure glaucoma were investigated. The diagnosis of angle-closure glaucoma was confirmed postoperatively in 258 eyes, in 201 of which the intraocular pressure became normal without further treatment and in 57 of which the postiridectomy IOP was elevated because of visible damage to the anterior chamber angle. Three eyes had open-angle glaucoma with a narrow angle. Six eyes had possible mixed (combined mechanism) glaucoma (2 2%). Mixed glaucoma is a rare, fortuitous combination of open-angle and angle-closure glaucoma rather than a distinct entity, and it might be advisable to avoid the term, which tends to be used for primary glaucomas of uncertain classification.The primary glaucomas have been classified into 3 groups: open-angle glaucoma, angle-closure (narrow-angle) glaucoma, and combined mechanism or mixed glaucoma (Shaffer, 1960). Since the heredity and pathogenesis of open-angle glaucoma and of angle-closure glaucoma are completely different, their coexistence should be a rare, chance combination. On the other hand most physicians would agree that the diagnosis of mixed glaucoma is made not uncommonly, especially when the differential diagnosis between open-angle and angleclosure glaucoma is uncertain.A promising method for assessing the incidence of mixed glaucoma is to study eyes which have undergone peripheral iridectomy: if angle-closure glaucoma was definitely present before the iridectomy and if glaucoma was still present postiridectomy in spite of an open, normal angle, the diagnosis of mixed glaucoma is probable.We could find no report of such an investigation in the literature. Materials and methodsThe records of 159 consecutive patients who underwent peripheral iridectomy for (presumed) primary angle-closure glaucoma were reviewed. Patients in whom the intraocular pressure (IOP) was higher than 20 mmHg on any occasion following iridectomy and in whom the elevated IOP was not clearly due to the presence of goniosynechiae obliterating a significant part of the angle were recalled for study. The examination of these patients consisted of

Defining "occludable" angles in population surveys: drainage angle width, peripheral anterior synechiae, and glaucomatous optic neuropathy in east Asian people

“…Hyams et al found that six of 267 eyes undergoing iridotomy for presumed primary angle closure glaucoma had ''mixed mechanism'' disease (2.2%), and a further three were felt to have POAG with narrow angles (1.1%). 13 If one assumes a background prevalence of PAS of 1%, and POAG of 2% in an adult population, one would expect a chance association of the two findings to occur in two in 10 000 people, if angle width were not brought into consideration. Currently, the potential for significant misclassification seems unduly prejudiced against diagnosis of PACG.…”

The fellow eye.

“…It is a necessary consequence that 30 to 55 % of iridectomies are unnecessary, but that fact causes no disquiet because there are few operative complications, and another acute attack rarely occurs. [2][3][4][5][6][7][8][9][10][11][12] If the fellow eye that will develop closed-angle glaucoma could be identified before the event, unnecessary iridectomies would be eliminated. This paper describes the result of a 10-year longitudinal study the purpose of which was to devise a scheme for selecting the eye that needs an iridectomy and to observe the behaviour of the untreated fellow eye.…”