Outcomes of newly referred patients with suspected angle closure: do we need to redefine the clinical pathways?

Abstract

Background/objectives: To investigate outcomes of referrals for suspected angle closure and explore whether anterior segment optical coherence tomography (AS-OCT) can be used to tighten triaging criteria in a glaucoma virtual clinic.

Subjects/methods: Retrospectively collected data. The first audit (04/2018-03/2019) identified referrals for suspected angle closure without other glaucoma-related findings (primary angle closure suspect (PACS) referrals). All patients underwent gonioscopy. The second audit (04-08/2019) identified patients with suspected angle closure in a virtual clinic. Management outcomes were assessed, using gonioscopy as reference standard. The outcomes of the second audit were re-audited after changing the triaging criterion from angle width <10° to iridotrabecular contact (ITC) in ≥1 quadrants on AS-OCT.

Results: Out of 1754 glaucoma referrals (first audit), 24.6% (431/1754) were PACS referrals. Of these, only 10.7% (42/393) had an occludable angle on gonioscopy, with 97.6% (41/42) being PACS. Of these, 78% (32/41) underwent laser peripheral iridotomy. Out of 137 referrals in the virtual clinic (second audit), 66.4% (91/137) were triaged to the face-to-face clinic. Of these, 31.9% (29/91) were discharged. AS-OCT had positive and negative predictive value of 74.3% (95% confidence intervals (CI) 57.8-86.0) and 82.1% (95% CI 70.0-90.2%), respectively, in detecting ITC in ≥1 quadrants. In the re-audit 45.9% (45/98) of those with suspected angle closure were triaged for gonioscopy, with 24.4% (11/45) of them being discharged.

Conclusion: PACS referrals represent a substantial burden to hospital-based services and their accuracy is low. ITC in ≥1 quadrants on AS-OCT can be useful in triaging those who need further evaluation with gonioscopy.

Fig. 1. Clinical audits on the outcomes of glaucoma referrals with suspected angle closure (Glaucoma Service, Moorfields Eye Hospital, London, UK).

The first audit (Moorfields Eye Hospital at Bedford) included all patients referred for suspected angle closure in the absence of other glaucoma-related findings. All patients were examined in the glaucoma face-to-face clinic with gonioscopy. The second audit (Moorfields Eye Hospital at Cayton Street) included newly referred patients who attended the virtual clinic within the above time frame and were suspected to have occludable angles, regardless of the initial reason for their referral. ZAP Zhongshan Angle Closure Prevention (ZAP) trial.