The Lang lab studies biological mechanisms that underpin development, homeostasis and disease. Historically, we have had a special interest in development of the visual system and in this context have identified mechanisms of embryonic induction and epithelial morphogenesis. The current passion of the Lang lab is an investigation of the intra- and extraocular light sensing pathways mediated by the opsin family members OPN3 (encephalopsin), OPN4 (melanopsin) and OPN5 (neuropsin). We have shown that within the eye OPN4 and OPN5 regulate light-dependent vascular development and that OPN5 light sensing determines myopia susceptibility. Unexpectedly, we have also found that OPN3 in adipocytes and OPN5 in the brain each mediate light sensing responses that regulate body temperature and energy homeostasis. Our ongoing work will continue to investigate these unusual light sensing pathways and relate their activities to human disease.