The College has received queries from members to clarify whether there is a specific cut off for glycaemic control, either measured via HbA1C or a blood glucose level on the day, beyond which it is unsafe to proceed with cataract surgery. There is anecdotal evidence of cataract surgery cases being cancelled for surgery if their HbA1C is above the cut off of 69mmol/mol (8.5%) following the joint guidance of the AAGBI, Joint British Diabetes Societies and Royal College of Anaesthetists in 2015.
This is a complex situation and has been extensively reviewed for the RCOphth local anaesthetic guidelines 2012 and also more recently in a 2016 paper by Kumar et al in the British Journal of Anaesthesia, which we recommend reading for the full evidence review.
There is evidence to show that good long-term control of blood glucose will reduce the likelihood of long-term complications such is retinopathy/maculopathy, infections, and the need for cataract surgery. However, there is no published evidence on the adverse effects of high intraoperative blood glucose on outcome after cataract surgery. The data collected by the NOD national cataract audit is not sufficient currently to robustly answer this question.
Whilst it is ideal for patients to have good diabetic control for any surgery, for local anaesthetic cataract surgery there also needs to be taken into account the lack of evidence for any certain safe or unsafe level of control, and the requirement for patients to obtain good visual function for their daily activities including their ability to see and manage their diabetic control and medications, and the ability for clinical professionals to safely see the fundus to manage any diabetic retinal problems. The College currently supports the view that diabetic patients undergoing cataract surgery should have their blood sugar controlled but does not consider that there is enough evidence to cancel the surgery above any one level of blood sugar or HbAiC. The decision to proceed or not should take into account the clinical and functional requirements of the patient, the wishes of the patient after discussion and explanation, and the clinical judgement of the surgeon, and of the anaesthetist if there is anaesthetic involvement in the care.
Peri-operative management of the surgical patient with diabetes 2015. Association of Anaesthetists of Great Britain and Ireland Membership of the Working Party: P. Barker, P. E. Creasey, K. Dhatariya, N. Levy, A. Lipp, M. H. Nathanson, N. Penfold, B. Watson and T. Woodcock. Anaesthesia 2015
Glycaemic control during cataract surgery under loco-regional anaesthesia: a growing problem and we are none the wiser. C. M. Kumar, E. Seet, T. Eke, K. Dhatariya and G. P. Joshi. British Journal of Anaesthesia 117 (6): 687–91 (2016)
RCOphth Local Anaesthetic guidelines 2012