The national survey of trabeculectomy. II. Variations in operative technique and outcome

Purpose There is a considerable body of literature relating to trabeculecto my, however, there are no data representative of the national experience of trabeculectomy in the United Kingdom (UK). The Department of Health funded a national survey of trabeculectomy to establish current practice patterns and the outcome of trabeculectomy in the National Health Service (NHS). In this paper we report variations in surgical technique and the national suc cess rate of trabeculectomy. Methods A cross-sectional survey was carried out of consultant ophthalmolog ists performing trabeculectomy in the NHS. Participants recruited their fou r most recent consecutive first-time trabeculectomy cases according to stud y eligibility criteria and data were collected by self-administered questio nnaire. Follow-up: 1 year posttrabeculectomy. Main outcome measure of succe ss: final intraocular pressure (IOP) less than two-thirds the pre-operative IOP. Secondary outcome measures of success: final IOP less than 21 mmHg an d visual field stability. Success was further defined as unqualified (exclu ding patients on antiglaucoma medications at final follow-up) or qualified (including patients on anti-glaucoma medications at final follow-up). The r elationship between variables characterising consultants' practice and main outcome measure was examined by chi-square test. Results Clinical outcome data were available for 1240 (85.3%) cases. There were wide variations in operative technique. The mean post-operative IOP wa s 14.4 mmHg (95% CI 14.2-14.7), which is a mean reduction of 11.8 mmHg (95% CI 11.4-12.2). An unqualified success, in terms of the main outcome measur e, was achieved in 66.6% of patients and a qualified success in 71.0% of ca ses. An unqualified success, in terms of a final IOP less than 21 mmHg, was achieved in 84.0% of cases and a qualified success in 92.0%. Visual fields were stable in 84.2%. Outcome was not related to consultants' specialist i nterest, level of activity, type of hospital or region. Conclusions The success rates reported in this paper represent the national experience of first-time trabeculectomy for open angle glaucoma in the UK. The national success rate at 1 year compares favourably with many studies in the literature. This survey provides valid and clinically relevant measu res of success for the production of guidelines and standards for audit at regional, local and individual level and a baseline for the comparison of n ew therapies.