title: Subregions of differing refractive power within the clear zone after experimental radial keratotomy.
abstract: After radial keratotomy (RK), some patients experience a mild decrease in best corrected visual acuity, visual distortion, or monocular diplopia. These optical effects of radial keratotomy are best explained by subregions of different refractive powers within the surgery-free clear zone. To investigate the topography of the clear zone, we performed four- and eight-incision radial keratotomy in eight cadaver eyes. After radial keratotomy, we found subregions within the clear zone of two types: 1) small, very flat regions at the ends of the radial incisions (seven of eight eyes), and 2) a series of concentric rings centered on the visual axis with a continuously progressive decline in refractive power toward the periphery of the clear zone (all eyes). The clear zone after radial keratotomy is often nipple-shaped, with a more myopic segment centrally and a more hyperopic region near the periphery of the clear zone.
authors.affiliation: Wilmer Ophthalmological Institute, Johns Hopkins Hospital, Baltimore, MD.
authors.forename: P F
authors.initials: PF
authors.lastname: Lopez
authors.forename: R K
authors.initials: RK
authors.lastname: Maloney
authors.forename: G G
authors.initials: GG
authors.lastname: Goodman
authors.forename: W J
authors.initials: WJ
authors.lastname: Stark
mesh_terms: D003315:Cornea / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007646:Keratotomy, Radial / Q000009:adverse effects*; D011183:Postoperative Complications; D012030:Refractive Errors / Q000209:etiology*; D014792:Visual Acuity