PurposeEndogenous endophthalmitis (EE) is a rare but serious ocular infection caused by the seeding of bacteria into the eye from a source elsewhere in the body. Studies suggest that EE accounts for 2 to 8% of all endophthalmitis.MethodsA prospective observational study was conducted using the British Ophthalmological Surveillance Unit reporting system. Questionnaires were sent to reporting Ophthalmologists in the UK to assess incidence, underlying aetiology, eye findings, management, and final outcomes in endogenous endophthalmitis over a 12-month period within the British Isles.ResultsSixty two cases reported with 48 initial questionnaires returned and 25 6-month follow-up questionnaires returned. The median age of patients affected was 57 years with youngest aged 2 years and oldest aged 85 years. Twenty three were male and 24 were female. The median visual acuity in the affected eye was 3 logMAR (range -0.1 to 5). Blood cultures were taken in 36 patients, 58% of which were positive. Vitreous biopsy was taken in 35 patients, 23% of which were culture positive. The visual function as assessed by visual acuity had significantly improved at 6 months with a median acuity of 0.18 logMAR (P=0.003).ConclusionsThe survey demonstrates the severe nature of endogenous endophthalmitis in patients with active infection or with risk factors for infection. Our study has demonstrated that at least half of the patients who were treated had significant vision improvement.