The British Ophthalmological Surveillance Unit: an evaluation of the first 3 years.

We report an evaluation of the British Ophthalmological Surveillance Unit (BOSU), a nationwide active surveillance scheme to assist with the case ascertainment of rare eye conditions. The evaluation assessed participation rates, study applications and research outputs. In addition, through an anonymous postal survey we ascertained the opinions of ophthalmologists regarding the usefulness, levels of feedback, barriers to participation and levels of case ascertainment. Over the first 3 years, the 4-month mean participation rate has improved from 58% to 71%. Ten studies have used this system for case ascertainment. To date three journal publications and 10 conference presentations have reported findings from these studies. It was observed that 582/870 (68%) questionnaires were returned by ophthalmologists, of whom 95% considered BOSU as very or quite useful. In all, 71% reported overall feedback to be sufficient. However, 34% requested greater feedback from research groups. Reported barriers to effective participation were 'having to remember the patient's identity' (52%) and paying for return postage of cards (22%). However, 72% of respondents did not consider the work involved in reporting a case to be prohibitive. Self-reported levels of case ascertainment by ophthalmologists for completed studies ranged between 72% and 95%. This population-based surveillance system provides an effective method for prospective case identification and subsequent data collection. It enables the study of sufficiently representative samples to allow meaningful epidemiological analysis and avoid bias. Its success relies upon the high level of support that it currently receives from ophthalmologists.