Apparatus and method for interfacing an ophthalmic surgical laser system with a patient's eye using a single-piece patient interface (PI). The PI includes a hollow shell, with an applanation lens and a flexible skirt at its lower end. Through channels are formed around the applanation lens to connect the spaces above and below the lens. When the PI is coupled to the laser system and the eye, the upper rim of the shell forms a seal with the laser system and the flexible skirt forms a seal with the eye. A vacuum is applied to the interior of the shell via a vacuum port on the laser system, and the vacuum is communicated to the space enclosed by the applanation lens, the skirt and the eye through the channels around the lens. A magnetic mechanism is also provided to hold the PI shell to the laser system.