A light source for coupling light into a medical device, particularly a surgical handheld device, preferably for use in ophthalmology, comprising a lamp (1), a light guide (2) extending from the lamp (1), and a power supply (3) for the lamp (1), is characterized in that the lamp (1) is arranged in an adapter-like housing (4), which comprises a connection (5) for the power sup ply (3) and a connection (6) for the light guide (2).