title: Evidence for a relative thinning of the peripheral cornea with age in white European subjects.
abstract: OBJECTIVE
  To investigate age-related differences in central and peripheral corneal thickness in humans with univariate and multivariate regression analyses.
  
  
  METHODS
  Orbscan II (Bausch & Lomb, Inc., Rochester, NY) pachymetry was used to assess the cornea in healthy, white European subjects. A corneal thickness profile across an 8-mm chord along the horizontal meridian was generated at 0.5-mm intervals. Univariate and multivariate regression analyses were used to assess any predictable age-related differences, especially in the peripheral cornea.
  
  
  RESULTS
  One hundred nine subjects (109 eyes), aged 18 to 82 years with a mean central corneal thickness (CCT) of 0.585 +/- 0.040 mm (+/- SD, no acoustic factor applied) showed no age-related differences of CCT (P = 0.381). Regression analyses indicated no substantial age-related differences at any location except at 4 mm from center on the nasal side (P = 0.036). However, if considered in relative terms as the corneal thickness profile index (CTPI), a just-significant, age-related, relative thinning was detected at 2.5 mm from center (P = 0.027, nasal). The thinning was even more notable at 3 mm (P < 0.001, r = -0.322) and was substantial at 4 mm (P < 0.001, r = -0.505). Multivariate regression analysis supported these results and indicated that CTPI was best predicted by a combination of age and posterior corneal curvature.
  
  
  CONCLUSIONS
  The results of this study provide evidence that comparing relative thicknesses emphasizes any age-related pachymetry differences and confirmed substantial age-related thinning of the peripheral cornea in healthy white European individuals. These findings should be considered in assessments of refractive surgery patients.
authors.affiliation: Department of Vision Sciences, Glasgow Caledonian University, Glasgow, Scotland, United Kingdom. sven.jonuscheit@gcal.ac.uk
authors.forename: Sven
authors.initials: S
authors.lastname: Jonuscheit
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Doughty