A nozzle unit for cross-linking of eye tissue is disclosed. The nozzle unit comprises a dosing device for providing a predefined dose of a photosensitizer, a pressure-generating device for generating a pressure in the dosing device, and an outlet nozzle for discharging the dose of the photosensitizer, in a puff-type manner and in the form of at least one stream or stream bundle, through an outlet opening of the outlet nozzle.