ABOUT 1940, it seemed desirable to have a single pair of glasses that would facilitate specific visual tasks without the necessity of wearing a loupe1 or changing glasses. Mr. Conrad Carlsen was asked to construct lenses that would fill the specified requirements. The spectacles are described now because of the interest shown in them by many ophthalmologists during the last 12 years.
The requirements were spectacles that would facilitate the following visual activities:
Permit distance vision without the necessity of bending the head too far forward.
Permit clear intermediate vision for tasks at about 20 in. (50 cm.), for example, reading the markings on trial frames and for picking up instruments in operating.
Permit reading at a distance of approximately 16 in. (40 cm.), a distance which also would be satisfactory for plastic surgery and muscle operations.
Permit clear vision and little strain on convergence when dilating puncta, removing
BERENS C. NEW QUADRIFOCAL SPECTACLE FOR THE PRESBYOPIC OPHTHALMOLOGIST. AMA Arch Ophthalmol. 1952;48(5):632–633. doi:10.1001/archopht.1952.00920010643012
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