Retinal calcium waves coordinate uniform tissue patterning of the Drosophila eye.

Optimal neural processing relies on precise tissue patterning across diverse cell types. Here, we show that spontaneous calcium waves arise among non-neuronal support cells in the developing Drosophila eye to drive retinal morphogenesis. These waves are initiated by Cad96Ca receptor tyrosine kinase signaling, triggering phospholipase C-γ-mediated calcium release from the endoplasmic reticulum. A cell type-specific "innexin code" coordinates wave propagation through a defined gap junction network among non-neuronal retinal cells, excluding photoreceptors. Wave intensity scales with ommatidial size, triggering stronger myosin II-driven apical contraction at interommatidial boundaries in larger ommatidia. This size-dependent mechanism compensates for early boundary irregularities, ensuring uniform ommatidial packing that is critical for precise optical architecture. Our findings reveal how synchronized calcium signaling among non-neuronal cells orchestrates tissue patterning in the developing nervous system.