Required to maintain the integrity of photoreceptor cells (By similarity). Specifically required for normal morphology of the photoreceptor ciliary pocket, and might thus facilitate protein trafficking between the photoreceptor inner and outer segments via the transition zone (By similarity). Localizes to discrete puncta at, or adjacent to, the photoreceptor connecting cilium. Highly expressed in cone photoreceptor outer segments (By similarity). Weakly expressed in rod photoreceptor outer segments (By similarity). May localize to the cilium axoneme (By similarity). May also be secreted into the interphotoreceptor extracellular matrix (By similarity). Belongs to the EYS family. Truncated N-terminus.