title: Multifocal corneal topographic changes with excimer laser photorefractive keratectomy.
abstract: Excimer laser photorefractive keratectomy can flatten the central cornea, thereby eliminating myopic refractive errors; in older patients, however, presbyopia limits satisfaction. Computer-assisted topographic analysis of corneas after refractive surgery indicates that a minority of patients achieve a multifocal lens effect, such that they maintain reasonable acuity over a range of defocus. We have purposefully attempted to create a multifocal refractive effect and have analyzed the subsequent topographies quantitatively to determine if multifocality was achieved. In corneas not operated on and plastic hemispheres, a fairly small range of corneal powers is observed; the range of powers is increased after a monofocal ablation. After multifocal ablations, a greater spread of surface powers is observed, often with a bimodal distribution, indicative of an apparent multifocal effect. These observations suggest that in some patients undergoing photorefractive keratectomy for myopia, it may be possible to reduce symptoms of presbyopia, although a decrease in image contrast or monocular diplopia may complicate this approach.
authors.affiliation: Doheny Eye Institute, Los Angeles, CA 90033.
authors.forename: H
authors.initials: H
authors.lastname: Moreira
authors.forename: J J
authors.initials: JJ
authors.lastname: Garbus
authors.forename: A
authors.initials: A
authors.lastname: Fasano
authors.forename: M
authors.initials: M
authors.lastname: Lee
authors.forename: T N
authors.initials: TN
authors.lastname: Clapham
authors.forename: P J
authors.initials: PJ
authors.lastname: McDonnell
mesh_terms: D000818:Animals; D003196:Computer Graphics; D003315:Cornea / Q000601:surgery*; D053685:Laser Therapy; D008768:Methylmethacrylates; D009216:Myopia / Q000601:surgery*; D011817:Rabbits
chemical_list: D008768:Methylmethacrylates