INCIDENCE OF ACUTE ANGLE CLOSURE GLAUCOMA IN THE NORTHERN IRELAND DIABETIC EYE SCREENING PROGRAMME.

Editor,

This project aimed to ascertain the risk of acute angle closure (AAC) after the administration of tropicamide within the Diabetic Eye Screening Programme Northern Ireland (DESPNI). DESPNI provides a regional screening service to all of those with diabetes mellitus in Northern Ireland. There are 112000 patients on the register, of these 87 000 have regular annual eye screening using fundus photography.1 At DESPNI, mydriasis using tropicamide can improve the quality of fundus images obtained. AAC is a rare complication of mydriasis, estimated risk of 0.3–0.03 %, and is an ophthalmic emergency that might lead to permanent visual loss if left untreated.2 During 2007-2010, of the 95265 DESPNI episodes with Tropicamide dilation, 2 cases were identified, giving the risk of 1 in 31 755 and annual incidence was 0.75 cases.3 The recommendations to DESPNI included clear instructions of AAC symptoms and emphasising the need for urgent treatment should they occur. This was after peer-to-peer education regarding AAC awareness in ophthalmic screening healthcare programme.

This audit aims to assess the incidence and management of AAC occurring within 72 hours of DESPNI attendance with tropicamide mydriasis between 01/09/2016 to 28/02/2021. A retrospective case-note review was carried out, cross referencing medical and DESPNI records, to identify relevant AAC episodes occurring within 72 hours of a DESPNI visit with mydriasis. The standards were extracted from ‘Ophthalmic Services Guidance Eye Drops Instillation by Unregistered Health Care Professionals for use within NHS Ophthalmic Services’. For this current audit, 159 patients were identified as having had AAC during 01/09/2016 to 28/02/2021. Only one had AAC within 72 hours of DESPNI’s tropicamide dilation and was successfully managed. Over the 54 months period of observation, 206334 patients were screening by DESPNI with a dilation rate of approximately 75%, so altogether 154750 patients were dilated. The incidence of AAC within the screening programme was calculated to be 1 event per 154750 episodes. The annual incidence of angle closure was 0.2 cases per year.

This improves our ability to inform patients of the low risk of AAC within DESPNI. The AAC incidence within DESPNI was calculated to be 1 event per 154750 episodes, this is less than reported in other publications such as the population-based Rotterdam Study, where AAC incidence was 3 in 10 000 following tropicamide mydriasis.4 We advocate the provision of clear instructions to patients in diabetic screening regarding access to emergency ophthalmic care following dilation to prevent visual loss in this rare event.

The authors declare no conflict of interest.

This project was funded by The Wellcome Trust.