A mechanism for extending and retracting a retainer strap for eyewear. The strap is disposed in one or both hollow temples of an eyeglass frame and is manually extended, retracted, and locked by an extension which slides in a port or passageway forming a track or slot disposed in one surface of the temple extending from the interior to the exterior of the temple. The extension provides the means to manually retract the strap from an extended position, which extended position is achieved by pulling out the strap from the rearward end, and may be used to form one component of a locking mechanism for the strap either in the extended or retracted position. The retainer straps may be either elastic, inelastic, or one of each to provide for different modes of use.