ARTICLES have appeared in popular magazines and newspapers suggesting trifocal glasses for general use.1 Manufacturers report a sharp increase in sales and now suggest that most wearers of bifocals would be better satisfied with trifocals. Nothing in the textbooks or the literature suggests the use of trifocal glasses except in certain occupational groups.2 Ophthalmologists otherwise prescribe trifocals only when requested.
In order to provide evidence as to whether presbyopes of all degrees and of all occupations would benefit by the use of trifocal glasses, I have during the past year made available to all my presbyopic patients trifocals at the same price as bifocals.3 The patients were assured that if they found trifocals objectionable in any way, bifocals would be supplied free of charge. Most patients were interested. and 50 tried them.
Except for the experiment, probably none of these patients would have obtained trifocals. Frankly, I
MILES PW. EXPERIMENT IN WHICH FIFTY PRESBYOPES WERE PROVIDED WITH TRIFOCAL GLASSES. AMA Arch Ophthalmol. 1951;46(5):542–548. doi:10.1001/archopht.1951.01700020555012