A disposable attachment to a medical inspection or speculum device is disclosed that improves control of a fiber optic light source utilized in conjunction with the medical device to provide illumination within an internal body cavity. The attachment comprises a hollow guide tube and support having an attachment mechanism, wherein the attachment is adapted to affix to a medical device while the guide tube allows the fiber optic light to be fed therethrough and into the body cavity of interest. The guide tube provides physicians with a readily attachable and disposable alternative to existing methods of handling light sources, which often require diligent guidance and sterilization after each patient. In use, the device allows physicians to accurately inspect and diagnose conditions within a cavity by providing a stable light source to an existing instrument, whereafter the guide tube may be removed and discarded, and further the light may remain sterile.