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May 1993

Corneal Bifocal Effects by Laser Photorefractive Keratectomy

Author Affiliations

Toronto, Ontario

Arch Ophthalmol. 1993;111(5):582. doi:10.1001/archopht.1993.01090050016007

To the Editor.  —The multifocal corneal topographic changes proposed by Moreira et al1 in the July 1992 issue of the Archives were most provocative. The potential for creating a bifocal effect by using the corneal surface is certainly a worthy goal for the surgeon. However, considering my experiences with wearers of bifocal contact lenses, I must admit concern for healthy-eyed subjects who may consider this procedure.A visual effect similar to that described by Moreira et al is probably produced by concentric zone bifocal contact lenses. Practitioners experienced in fitting bifocal contact lenses have long heard the patient complaints regarding the problems associated with contact lenses that function by means of the simultaneous-image principle.A bifocal of this type divides the ambient light that enters the pupil into distance imagery and near imagery. This division of light affects the flux density and distribution of the optical image on the

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