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Abstract #16899 Published in IGR 9-1
Diurnal variation of central corneal thickness and Goldmann applanation tonometry estimates of intraocular pressure
Hamilton KE; Pye DC; Aggarwala S; Evian S; Khosla J; Perera RJournal of Glaucoma 2007; 16: 29-35
See also comment(s) by Teruyo Kida •
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 mmHg (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.
Dr. K.E. Hamilton, School of Optometry and Vision Science, University of New South Wales, Sydney NSW 2052, Australia
Classification:
2.2 Cornea (Part of: 2 Anatomical structures in glaucoma)
6.1.3 Factors affecting IOP (Part of: 6 Clinical examination methods > 6.1 Intraocular pressure measurement; factors affecting IOP)
