title: Characteristics of ocular higher-order aberrations in patients with pellucid marginal corneal degeneration.
abstract: OBJECTIVE
  To evaluate the characteristics of higher-order aberrations (HOAs) in eyes with pellucid marginal corneal degeneration (PMCD).
  
  
  METHODS
  Department of Ophthalmology, Osaka University Medical School, Osaka, Japan.
  
  
  METHODS
  Ocular HOAs were measured by aberrometry in 20 eyes with PMCD (PMCD group), 76 eyes with keratoconus (KC group), and 105 normal eyes (control group) with a 4.0 mm pupil. The magnitudes and axes of trefoil, coma, tetrafoil, and secondary astigmatism and the magnitude of spherical aberration were compared between the 3 groups using vector analysis of Zernike terms.
  
  
  RESULTS
  The mean axes of coma in the PMCD group (85.5 degrees) and KC group (82.5 degrees) were opposite the axis in the control group (253.7 degrees). The magnitude of coma was significantly lower in the PMCD group (0.27 microm +/- 0.19 [SD]) than in the KC group (0.70 +/- 0.37 microm) (P < .05). The mean axes of trefoil in the PMCD group (27.1 degrees) and control group (35.4 degrees) were opposite the axis in the KC group (93.8 degrees). The magnitude of spherical aberration was significantly higher in the PMCD group (0.086 +/- 0.10 microm) than in the KC group (-0.030 +/- 0.13 microm) (P < .05); the spherical aberration signs were opposite in the groups.
  
  
  CONCLUSIONS
  Although PMCD and KC are categorized as noninflammatory corneal thinning disorders, the HOA patterns in the 2 groups differed, possibly due to differences in the positions of the corneal apex. PMCD and KC may cause distinctively different deterioration in the quality of vision.
authors.affiliation: Department of Ophthalmology, Osaka University Medical School, Osaka, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Oie
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Maeda
authors.forename: Ryo
authors.initials: R
authors.lastname: Kosaki
authors.forename: Asaki
authors.initials: A
authors.lastname: Suzaki
authors.forename: Yoko
authors.initials: Y
authors.lastname: Hirohara
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Mihashi
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hori
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Inoue
authors.forename: Kohji
authors.initials: K
authors.lastname: Nishida
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujikado
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Tano
mesh_terms: D000328:Adult; D003315:Cornea / Q000473:pathology*; D003316:Corneal Diseases / Q000175:diagnosis*; D019781:Corneal Topography; D004108:Dilatation, Pathologic / Q000175:diagnosis; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis; D008297:Male; D012030:Refractive Errors / Q000175:diagnosis*