Inserting an intravenous line is difficult in many patients due to obscured veins and may require several puncture attempts (for example, to insert an IV line), which is painful for the patient. Twistlight makes peripheral veins visible with the help of LED in a diagnostically relevant wavelength, and assists the medical personnel in identifying a suitable vein quickly. The device is ergonomically designed based on the accustomed action sequence of the person performing the puncture. Thanks to the integrated catheter feed, the patent-pending system can be operated single-handedly, so that the other hand can be freed up to hold the patient down when needed. There is no tedious ‘relearning’ required when using the Twistlight. The battery-operated and handy device can be used in hospitals and medical practices, as well as for emergencies.