title: Higher-order aberrations when wearing sphere and toric soft contact lenses.
abstract: OBJECTIVE
  To determine the on-eye effect of spherical and toric contact lens design on higher-order aberrations (HOA).
  
  
  METHODS
  Thirty eyes (15 subjects) entered a masked, randomized, cross-over study. Each eye was fitted with the spherical and toric lens of the following brands in random order: Acuvue Advance, Biomedics 55, Frequency 55, and SofLens 66. HOAs were measured using the Zywave II Aberrometer over a 6-mm aperture up to fifth order. A linear model accounting for the fixed effect of lens type and random effects of subject and eye was created. Paired t-tests were completed between lens brands within the spherical and toric lenses and between the spherical and toric lens within each brand. Best-corrected visual acuity (VA) was measured and compared.
  
  
  RESULTS
  No clinically meaningful differences in total HOAs were found between brands or between the spherical and toric lens within a brand. Positive spherical aberration (SA) was reduced by all spherical and toric lenses compared to wearing no lens by 0.07 to 0.23 microm (p < 0.0001). Frequency toric induced the greatest change in SA. The thin-zone design lens (Acuvue Advance for Astigmatism) had a statistically different amount of vertical coma (-0.04 microm) than the three prism-balast toric lenses (0.11 to 0.23 microm; p < 0.0001). SofLens toric had the greatest amount of vertical coma, but better VA than Acuvue Advance for Astigmatism and Frequency toric. With the exception of Acuvue Advance for Astigmatism, toric lenses had greater absolute magnitude of vertical coma than their sphere counterparts (all p < 0.002). No other significant HOA differences were observed.
  
  
  CONCLUSIONS
  Toric contact lenses with prism-ballast designs demonstrated more vertical coma, but better VA. Positive SA was reduced by spherical and toric contact lenses. The visual quality effect of lens design and material on induced HOAs warrants further investigation.
authors.affiliation: The Ohio State University, College of Optometry, Columbus, Ohio 43210, USA. dberntsen@optometry.osu.edu
authors.forename: David A
authors.initials: DA
authors.lastname: Berntsen
authors.forename: Mohinder M
authors.initials: MM
authors.lastname: Merchea
authors.forename: Kathryn
authors.initials: K
authors.lastname: Richdale
authors.forename: Carla J
authors.initials: CJ
authors.lastname: Mack
authors.forename: Joseph T
authors.initials: JT
authors.lastname: Barr
mesh_terms: D000293:Adolescent; D001251:Astigmatism / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D003263:Contact Lenses, Hydrophilic; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009216:Myopia / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D011446:Prospective Studies; D012029:Refraction, Ocular; D013997:Time Factors; D016896:Treatment Outcome