title: Impact of Zernike-fit error on simulated high- and low-contrast acuity in keratoconus: implications for using Zernike-based corrections.
abstract: This study examines the extent to which a Zernike-based optical correction can restore acuity in keratoconus as a function of disease severity and contrast level. Increasingly complete Zernike corrections in the presence of Zernike-fit error were simulated. Acuity for keratoconic eyes with <60 D maximum corneal power reached 20/13 with a fifth-order Zernike correction under high-contrast conditions and exhibited a loss of 0.1 logMAR (minimum angle of resolution) (from 20/32 to 20/40) for low-contrast conditions. Acuity for keratoconic eyes with >60 D maximum corneal power approached 20/13 with sixth-tenth-order corrections under high-contrast conditions but did not return to similar levels with a tenth-order correction for low-contrast conditions. The results suggest that fit error affects visual performance for more difficult tasks and that restoring high-contrast acuity (20/16 or better) using a fifth-order Zernike correction is not limited by Zernike=fit error for over 88% of keratoconus cases.
authors.affiliation: Visual Optics Institute, College of Optometry, University of Houston, Texas 77204-2020, USA. jmarsack@optometry.uh.edu
authors.forename: Jason D
authors.initials: JD
authors.lastname: Marsack
authors.forename: Konrad
authors.initials: K
authors.lastname: Pesudovs
authors.forename: Edwin J
authors.initials: EJ
authors.lastname: Sarver
authors.forename: Raymond A
authors.initials: RA
authors.lastname: Applegate
mesh_terms: D003198:Computer Simulation; D015350:Contrast Sensitivity; D019781:Corneal Topography / Q000379:methods*; D006801:Humans; D007640:Keratoconus / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D008954:Models, Biological; D012030:Refractive Errors / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D012031:Refractometry / Q000379:methods; D013813:Therapy, Computer-Assisted / Q000379:methods*; D014786:Vision Disorders / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D014792:Visual Acuity