Advantage is taken of the fact that in optical navigation devices it is possible to measure the intensity of light impacting the pixel array of photo-diodes. Based upon such an intensity determination, a feedback signal is used to reduce the intensity of the light to a point where it is equal to or less than a predetermined value. In one embodiment, the discharge rate of a capacitive power supply is used to determine the intensity of the light source impacting the pixels. When the discharge rate is faster than a given amount the inference is that the light intensity is too great and power is reduced to the light source to reduce the intensity.