Illumination systems are described that can include one or more light sources, which can include LEDs, one or more lenses, and one or more optical fibers. A handheld, portable, and surgical intraocular illumination system is disclosed that is disposable, low-cost, and efficient. A surgeon can have direct control of turning the illuminator on and off and adjusting the intensity via a simple control ergonomically placed on the handpiece and/or voice activated control. A coupling is provided, such as through an endo-probe, which is coupled to the one or more light sources. A user input device can be included that is operable to transmit to a feedback controller a first signal based on a user-selected light intensity. The feedback controller can, in response to the first signal, transmit a second signal to the power source for altering the power provided by the power source to the illumination system.