US Patent 7762661 Glasses with two position lenses

Glasses such as bifocals, which have refractive lenses which are rotatable at least between two positions. A manual control rotates the lenses such that if bifocal, the relatively small, high magnification zone of each lens can be moved to a high position opposed to the usual low position of fixed bifocals. The user is spared the necessity of holding the head at an awkward posture when viewing overhead objects.