Abstract: A flat form gas discharge lamp is disclosed which includes glass front and back plates mounted together and in which the front plate is formed with a plurality of channels which are sealed to confine an ionizable medium. The channels are oriented in parallel relationship and are separated by gaps. Optical means is placed in the gaps for intercepting secondary light which is transmitted laterally from side walls of the channels and redirected toward the front of the lamp. Secondary light in combination with the primary transmitted through front walls of the channels provides illumination across an area with optimum brightness uniformity and efficiency.