Object To assess whether a single daytime measurement of central corneal thickness (CCT) using ultrasonic pachymetry can give a representative assessment of mean CCT in patients with suspected glaucoma.
Method  CCT was measured by a single observer in 60 eyes of 30 patients with suspected glaucoma using an ultrasonic pachymeter. Five measurements were made at 8:00 AM, 10:00 AM, 12:00 AM, 2:00 PM and 4:00 PM.
Result  There was no significant CCT changes in this group of patients with suspected glaucoma during the different daytime.
Conclusion  A single daytime measurement of CCT is sufficient when assessing patients with suspected glaucoma.