Diurnal variation of central corneal thickness and Goldmann applanation tonometry estimates of intraocular pressure

J Glaucoma. 2007 Jan;16(1):29-35. doi: 10.1097/IJG.0b013e31802b350f.


Purpose: To determine whether there is a temporal relationship between the diurnal variation of central corneal thickness (CCT) and intraocular pressure (IOP) by Goldmann applanation tonometry in young normal human participants in vivo.

Methods: Twenty-five eyes of 25 young healthy normal participants were examined in a prospective observational cross-sectional study. IOP, CCT and corneal curvature were measured using standard clinical techniques over a 24-hour period, and the temporal interrelationships between these parameters were examined.

Results: The overnight change in IOP measured by Goldmann tonometry was 3.1+/-2.4 mm Hg (P<0.001), CCT was 20.1+/-10.9 mum (P=0.016), with no statistical change in central corneal curvature (0.05 mm, P=0.477, paired t test with Bonferroni correction). Both IOP and CCT were highest on awakening at 7:00 then dropped rapidly to baseline levels by 9:00 (linear mixed models), and these two parameters were highly correlated (r=0.978, P<0.001). After 9:00, there was no correlation between these parameters (r=-0.453, P=0.260).

Conclusions: The results of this study have highlighted a potential link between the diurnal variation of CCT and the accuracy of Goldmann tonometry estimates of IOP during the first 2 hours after awakening. Clinicians should be wary of using Goldmann tonometry to estimate IOP until the overnight increase in CCT has resolved.

MeSH terms

  • Adolescent
  • Adult
  • Anthropometry
  • Circadian Rhythm / physiology*
  • Cornea / anatomy & histology*
  • Cross-Sectional Studies
  • Humans
  • Intraocular Pressure / physiology*
  • Prospective Studies
  • Tonometry, Ocular