Circadian variations in central corneal thickness and intraocular pressure in patients with glaucoma

Aim: To analyse 24 hour variations in intraocular pressure ( IOP) and central corneal thickness ( CCT) in a group of glaucomatous patients. Methods: 30 patients with primary open angle glaucoma were hospitalised and underwent circadian evaluations ( at 8 pm, midnight, 4 am, 8 am, noon, and 4 pm) of supine and sitting IOP, respectively, measured using a Perkins and a Goldmann tonometer, and CCT measured using an ultrasonic pachymeter ( the mean value of three measurements within 5 mm). All patients were treated with timolol 0.5% twice daily and latanoprost 0.005% once daily. Results: Mean supine IOP was 15.3 ( SD 3.7) mmHg ( range 10 - 25), with circadian fluctuations of 7.3 ( 3.3) mmHg. Mean sitting IOP was 15.1 ( 3.9) mmHg ( range 8 - 26), with circadian fluctuations of 5.4 ( 3.1) mmHg. Mean CCT was 534 ( 39) mm ( range 443 - 637 mm) with circadian fluctuations of 16.5 ( 6.2) mm ( range 6 - 31 mm). Both the within patient and within time point fluctuations in CCT were statistically significant ( p, 0.0001, ANOVA). Conclusions: The authors found considerable fluctuations in 24 hour IOP. The circadian fluctuations in CCT were small and, although statistically significant, did not seem to interfere with the circadian IOP assessment.