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

Eye Clinic, Department of Medicine, Surgery, and Odontoiatry, San Paolo Hospital, University of Milan, Milan, Italy

Correspondence to:
Correspondence to:
Nicola Orzalesi
Clinica Oculistica, Ospedale San Paolo, Via di Rudinì, 8, 20142 Milan, Italy; fogagnolopaolo{at}libero.it

ABSTRACT
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 µm). 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) mm Hg (range 10–25), with circadian fluctuations of 7.3 (3.3) mm Hg. Mean sitting IOP was 15.1 (3.9) mm Hg (range 8–26), with circadian fluctuations of 5.4 (3.1) mm Hg. Mean CCT was 534 (39) µm (range 443–637 µm) with circadian fluctuations of 16.5 (6.2) µm (range 6–31 µm). 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.

Abbreviations: CCT, central corneal thickness; COV, coefficient of variation; CPSD, corrected pattern standard deviation; IOP, intraocular pressure; LTG, low tension glaucoma; MD, mean defect; POAG, primary open angle glaucoma

Keywords: glaucoma; intraocular pressure; corneal central thickness; pachymetry; circadian rhythm

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