A system for providing a therapeutic treatment to a patient's eye, the system comprising: an aiming beam source configured to transmit an aiming beam along an aiming beam path; a treatment beam source configured to transmit a treatment beam along a treatment beam path; an adapter device couplable with the treatment beam source and an ophthalmic imaging instrument, the treatment beam source configured to transmit the treatment beam from a treatment beam output, the ophthalmic imaging instrument having an imaging system configurable for viewing a retina of an eye of a patient, the adapter device comprising an interface configured to couple with the treatment beam output of the treatment beam source so as to receive the treatment beam, and an aiming device disposed along the treatment beam path from the interface and along the aiming beam path from the aiming beam source, the aiming device configured to scan the aiming beam from the aiming beam source across the retina to indicate a treatment area when a user is viewing the retina with the imaging system, and to scan the treatment beam onto the treatment area; and a control unit coupled to the aiming device and configured to: define, via the aiming beam, a treatment boundary on the retinal tissue separating a region of the retina into a first area and a second area, the treatment boundary including a pattern of recurring geometric shapes; and direct the treatment beam onto the retina within one or more of the geometric shapes defined by the aiming beam so as to deliver the therapeutic treatment to the retinal tissue of the patient's eye; wherein the control unit is configured to switch the aiming beam source on while the treatment beam source is switched off to define the treatment boundary and then to switch the aiming beam source off while the treatment beam source is fired at target tissue within the treatment boundary, and wherein, between subsequent firings of the treatment beam source, the aiming beam is switched on to redefine the treatment boundary on the retinal tissue, the visual effect being a solid treatment boundary. an aiming beam source configured to transmit an aiming beam along an aiming beam path; a treatment beam source configured to transmit a treatment beam along a treatment beam path; an adapter device couplable with the treatment beam source and an ophthalmic imaging instrument, the treatment beam source configured to transmit the treatment beam from a treatment beam output, the ophthalmic imaging instrument having an imaging system configurable for viewing a retina of an eye of a patient, the adapter device comprising an interface configured to couple with the treatment beam output of the treatment beam source so as to receive the treatment beam, and an aiming device disposed along the treatment beam path from the interface and along the aiming beam path from the aiming beam source, the aiming device configured to scan the aiming beam from the aiming beam source across the retina to indicate a treatment area when a user is viewing the retina with the imaging system, and to scan the treatment beam onto the treatment area; and a control unit coupled to the aiming device and configured to: define, via the aiming beam, a treatment boundary on the retinal tissue separating a region of the retina into a first area and a second area, the treatment boundary including a pattern of recurring geometric shapes; and direct the treatment beam onto the retina within one or more of the geometric shapes defined by the aiming beam so as to deliver the therapeutic treatment to the retinal tissue of the patient's eye; wherein the control unit is configured to switch the aiming beam source on while the treatment beam source is switched off to define the treatment boundary and then to switch the aiming beam source off while the treatment beam source is fired at target tissue within the treatment boundary, and wherein, between subsequent firings of the treatment beam source, the aiming beam is switched on to redefine the treatment boundary on the retinal tissue, the visual effect being a solid treatment boundary.