Device for shielding endoscopic optics with a fluid barrier

The present embodiments provide systems and methods suitable for delivering an agent including a plurality of particles to a target site. In example embodiments, a system suitable for delivering an agent to a target site includes a catheter having a first wall defining a lumen sized for delivery of the agent to the target site. The catheter has a distal end terminating with a primary opening of the lumen, an opposing proximal end, and a longitudinal axis extending between the distal end and the proximal end. At least one secondary opening is formed at the distal end, wherein the secondary opening is configured to allow fluid to flow through the secondary opening to create a steady flow of fluid at an angle with respect to the longitudinal axis and prevent the plurality of particles from flowing through the secondary opening.