A system includes a radiation source, one or more beam-directing elements, and a controller. The controller is configured to cause the radiation source to emit one or more aiming beams at the beam-directing elements such that the aiming beams are directed, by the beam-directing elements, toward an eye of a patient, to verify that each of the aiming beams is properly directed by the beam-directing elements, and, in response to verifying that each of the aiming beams is properly directed by the beam-directing elements, to treat the eye by causing the radiation source to irradiate one or more target regions of the eye with respective treatment beams. Other embodiments are also described.