Binocular magnifiers worn with a head band are routinely made to be worn without glasses or with single-vision glasses. These magnifiers are easily adjusted upward. However, it is impossible to adjust them downward over glasses beyond a certain point. The user thus at times may have to tilt his head awkwardly down and his eyes up. He cannot get the magnifiers down far enough to use with bifocal glasses.
In order to overcome this difficulty a "Twin Loupe" * (in this instance, a bifocal pair, 3 X magnification above and 1¾ X below) was modified as follows (Figure).
With a metal saw the aluminum portion of the magnifier was divided horizontally into two halves. The anterior section was dropped straight down approximately 1⅛ in. The two halves were bolted together in the new position with one piece of flat connecting metal on each side.
The new magnifiers can easily be moved
HUBBARD WB. An Improved Binocular Magnifier. AMA Arch Ophthalmol. 1959;61(1):141. doi:10.1001/archopht.1959.00940090143020