ISO 10939:2017, together with ISO 15004‑1 and ISO 15004‑2, specifies requirements and test methods for slit-lamp microscopes to provide slit illumination and observation under magnification of the eye and its adnexa. ISO 10939:2017 is not applicable to microscope accessories, e.g. photographic equipment and lasers. ISO 10939:2017 takes precedence over ISO 15004‑1 and ISO 15004‑2, if differences exist.