The advantages and disadvantages of bifocal lenses

Service d'Ophtalmologie, Hôpital Erasme, Université Libre de Bruxelles.
Bulletin de la Société belge d'ophtalmologie 02/1997; 264:71-8.
Source: PubMed


The bifocal glasses present three main disadvantages: the jump of the image when the visual axis passes from the far vision glass to the reading segment, the prismatic effect on the near vision point that entails an apparent displacement of the fixed object as well as a degradation of the quality of its image, and the absence of intermediate vision in total presbyopia. Bifocals however keep their indications, even after the availability of the progressive glasses, by people accustomed with this kind of correction, and by others who are not supporting deformations in the lateral vision of the progressive glasses. Suggestions are made for choosing the model of bifocal which is the most appropriate in function of the different situations.

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    • "It would be similarly unethical to compare bifocal and varifocal lenses as generic products against single vision lenses for most wearers. However, despite the clear commercial success of the products, even the peer reviewed evidence for preference of varifocals over bifocals (Borish and Hitzeman, 1983; Thorn and Baker, 1984; Boroyan et al., 1995; Markovits et al., 1995; Krause, 1996) is far from conclusive (Hitzeman and Myers, 1985; Krause, 1996; Zanen, 1997). There is only anecdote to show that bifocal use has not declined in the UK solely as a result of the death of existing wearers, the retirement of doubting opticians, and the pro-active and more profitable selling of varifocals by practitioners made more confident by success itself. "
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