Abstract
Abstract: :
Aim: To analyse variations of central corneal thickness (CCT) over 24 hours in a group of glaucomatous patients. Methods: 23 glaucomatous patients were hospitalized and underwent a circadian evaluation of CCT and intraocular pressure (IOP). All patients had abnormal visual fields and abnormal optic nerve heads and were on therapy with timolol 0.5% twice–a–day and latanoprost 0.005% once–a–day. CCT and IOP were measured at 4, 8, 12 a.m. and at 4, 8, 12 p.m. All measurements were performed by a single evaluator with patient on sitting position; CCT was evaluated as the mean value of 3 measurements. At each time–point, slit–lamp examination was performed to ensure absence of corneal epithelial defects that may interfere with CCT assessment; then CCT was performed using DGH 2000 AP ultrasonic pachymeter (DGH Technology Inc., San Diego, USA); finally, IOP was evaluated with Goldmann tonometer. Results: Mean CCT was 540 ± 32 microns (range: 479–599 microns). Mean CCT values were very similar at each time–point during 24 hours (P = 0.1, ANOVA), with a mean standard deviation of 4.3 microns. Mean individual patient CCT variation was 17.2 ± 6.6 microns (range: 6–25 microns, 1.1–5%) during the 24 hours. Mean IOP was 14.5 ± 2.4 mmHg (range: 9–22), with mean individual fluctuactions of 5.0 ± 2.1 mmHg during 24 hours. Conclusions: CCT is an important diagnostic and prognostic parameter for glaucoma. The present study demonstrated that CCT does not significantly fluctuate over 24–hours; besides, significant IOP fluctuactions were found. As a consequence, CCT variations do not significantly interfere with circadian IOP assessment, as IOP adjustment for CCT fluctuations is largely within the limits of inter– and intra– operator variability for Goldmann tonometry.
Keywords: intraocular pressure