title: Central versus thinnest pachymetry of the cornea and thinnest point vector length: impact of ocular side, refractive state, age, and sex.
abstract: OBJECTIVE
  To quantify the difference in corneal thickness between the central and thinnest point (ΔCCT-TPCT) and the distance between the center of the cornea and its thinnest point (TPCT vector length) and to explore the impact of ocular side, refractive state, age, and sex.
  
  
  METHODS
  Multicenter, retrospective, cross-sectional study. Medical records of 8054 eyes of 4027 refractive surgery candidates were reviewed. The correlation between ΔCCT-TPCT and TPCT vector length (Pentacam) and the variables refractive state, age, and sex were assessed. Spearman correlations, t tests, analysis of variance, analysis of covariance, and multiple regression models were used.
  
  
  RESULTS
  ΔCCT-TPCT was higher in the left eyes of myopic (3.03 ± 2.29 µm) and hyperopic (4.97 ± 3.19 µm) subjects compared with myopic (2.39 ± 2.28 µm) and hyperopic (4.77 ± 3.97 µm; P < 0.05) right eyes. ΔCCT-TPCT was higher in hyperopic than in myopic (P < 0.001) eyes. TPCT vector length was 0.62 ± 0.28 mm for the right eye and 0.69 ± 0.24 mm for the left eye (P < 0.001). TPCT vector length tended to increase with advancing age. Age had the strongest independent effect on TPCT vector length in myopic (η = 0.018; P < 0.001) and hyperopic (η = 0.028; P = 0.006) right eyes. No difference was observed between male and female subjects. The correlations between ΔCCT-TPCT and TPCT vector length were strong (r > 0.8; P < 0.001).
  
  
  CONCLUSIONS
  As a result of the significant differences found, normative data on ocular side, refractive state, and age should ideally be incorporated into ΔCCT-TPCT and TPCT vector length reference values.
authors.affiliation: Department of Ophthalmology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany. slinke@uke.uni-hamburg.de
authors.forename: Stephan J
authors.initials: SJ
authors.lastname: Linke
authors.forename: Tim
authors.initials: T
authors.lastname: Ceyrowski
authors.forename: Johannes
authors.initials: J
authors.lastname: Steinberg
authors.forename: Krister
authors.initials: K
authors.lastname: Kuhnhardt
authors.forename: Gisbert
authors.initials: G
authors.lastname: Richard
authors.forename: Toam
authors.initials: T
authors.lastname: Katz
mesh_terms: D000328:Adult; D000367:Age Factors; D003315:Cornea / Q000473:pathology*; D063171:Corneal Pachymetry; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000473:pathology*; D012029:Refraction, Ocular; D012189:Retrospective Studies; D012737:Sex Factors; D014792:Visual Acuity