This invention relates to the field of optical imaging. More specifically, it relates to fluorescent probes capable of effectively targeting prostate-specific membrane antigen (PSMA) and comprising heptamethrin dye having near-infrared (NIR) emission. The invention also relates to methods for preparing these compounds, pharmaceutical compositions and kits for introducing these compounds, and methods for using them as optical diagnostic agents in the imaging or treatment of diseases, particularly prostatecancer.