Currently, ophthalmic photographers and clinicians write reports detailing the location and types of disease visible in a patient's photograph. When colleagues wish to review the patient's case file, they must match the report with the image. This is both inefficient and inaccurate. As a solution to these problems, we present Oxalis, a distributed, extensible image annotation architecture, implemented in the Java programming language. Oxalis enables a user to: 1) display a digital image, 2), annotate the image with diagnoses and pathologies using a freeform drawing tool, 3) group images for comparison, and 4) assign images and groups to schematic templates for clarity. Images and annotations, as well as other records used by the system, are stored in a central database where they can be accessed by multiple users simultaneously, regardless of physical locality. The design of Oxalis enables developers to modify existing system components or add new ones, such as display capabilities for a new image format, without editing or recompiling the entire system. System components can elect to be notified when data records are created, modified, or removed, and can access the most current system data at any point. While Oxalis was designed for ophthalmic images, it represents a generic architecture for image annotation applications
