Vision preservation system for medical devices

The present disclosure includes vision preservation systems for medical devices, such as cryospray devices for use with endoscopes. Exemplary embodiments provide a distal attachment in the form of a shroud or cap that mounts to the end of a flexible endoscope. A purging fluid supply mechanism is provided along the length of the endoscope, providing a channel for purging fluid, such as gas, to communicate between the endoscope tip and an external gas supply. The cap or shroud assembly incorporates a lens clearing flow field adjustment mechanism, such as nozzles, designed to direct warm (room temperature or higher) purging fluid across a lens at the scope tip. Another flow deflection mechanism, such as a guide or nozzle, may be included with the cap to direct purging fluid at an angle away from the lens.