Choi, B. J.; Chen, Y.-C.; Desplan, C.

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. Waves are initiated by Cad96Ca receptor tyrosine kinase signaling, triggering PLCgamma-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 contractions at interommatidial boundaries in larger ommatidia. This size-dependent mechanism compensates for early boundary irregularities, ensuring uniform ommatidial packing critical for precise optical architecture. Our findings reveal how synchronized calcium signaling among non-neuronal cells orchestrates tissue patterning in the developing nervous system.