The aim of this study is to apply a diagnostic test called 'metagenomic sequencing' to identify the involvement of potential infections in patients with ocular inflammation, where this hasn't been detected by currently available standard testing. For many people with ocular inflammation, no cause is ever found for their disease. In some cases, an infection or infectious trigger is suspected, but currently available tests are inadequate. Metagenomic sequencing can identify almost every globally known infection (bacteria, virus, fungi, parasites) in a sample. Therefore, it has the potential to identify an infection that has caused or triggered ocular inflammation, and as a consequence may help to identify specific treatments. It has the potential to improve our understanding of how to diagnose and treat people with this problem. This study will allow us to test the technique that has been previously optimised for brain infections, on ocular fluids. Participants will be 18 years of age or over and have active ocular inflammation which is suspected to be due to an infection, or an autoimmune process which has been triggered by an infection, but identification of this infection has not been possible using the investigations available as part of standard NHS care. Participants will be identified by the treating clinical team as requiring a sample of fluid from inside of the eye, and some of this fluid will be sent for metagenomic sequencing alongside standard testing. This study will be conducted at Moorfields Eye Hospital, London and will last for approximately a year. Participants will undergo additional non-invasive ocular imaging on the day of their clinic visit, but will not have to attend any additional research visits.