Chemical warfare and the use of mustard gas on civilian population poses a major risk. Vesicating agents, such as mustard gas, cause severe damage to the corneas that can result in blindness and severe loss of sight. There are currently limited therapeutic options for treatment of damage caused by vesicating agents. To enable the rapid development of much needed medical countermeasures, the proposed work will test the possibility of drug repurposing. Drug repurposing strategies are based on the identification of new uses for existing drugs. Drug repurposing is a demonstrated successful strategy that can lower the cost of drug development and reduce development time. The key challenge in drug repurposing is the need to identify novel drug-disease relationships. To address this challenge we will deploy a set of innovative microscopy approaches that will provide rich data on the subtle aspects of the impact existing drugs have on corneal healing from chemical injury. Specifically, in Aim #1 we will perform a chemical screen of 770 existing drugs using live, organ culture, image-based assay. Mice corneas will be imaged for 48 hours after wound and sophisticated computer vision algorithm will be used to extract data on stem cell proliferation, cell death, cell migration, and wound closure. In Aim #2 we will construct spatiotemporal cornea-specific cell atlas of migration, proliferation, inflammatory signaling and gene expression response to chemical injury for controls, and drug-treated corneas. The cell atlases will provide a key resource on the process of chemical injury, the mechanism of action of existing therapies, and the mechanism of action of the most promising new drugs identified in Aim #1. Collectively, the results of this work will exploit the possibility of drug repurposing for the treatment of ocular injury caused by vesicants. The resource we will generate, i.e .the information on existing drugs and the detailed cell atlases of the process of healing will build the foundation for the rapid future development of much needed medical countermeasures.