Is corneal thickness measurement reliable and useful?

We evaluated the accuracy and the reproducibility of central corneal thickness measurements using an ultrasound pachymeter, and its usefulness in clinical practice. We calculated the intra-observer, inter-observer, and inter-session variability in control subjects (n = 38). We observed the diurnal variation (n = 8) and the role of surgery (n = 12) on central corneal thickness. We measured and compared central corneal thickness and intraocular pressure in 6 groups (control subjects n = 134, primary open-angle glaucoma n = 111, ocular hypertension n = 66, normal tension glaucoma n = 12, diabetes mellitus n = 62, corneal graft n = 27). We studied the influence of dorzolamide on central corneal thickness (n = 16). The intra-observer variability was 9 +/- 4 microns, whereas the inter-observer and inter-session variabilities were 4 microns and 5% m respectively. The central corneal thickness in patients with ocular hypertension (587 +/- 41 microns) was significantly greater than control subjects (548 +/- 32 microns) and all the other groups (p < 0.001). No influence of dorzolamide was observed on central corneal thickness. Central corneal thickness assessed with an ultrasound pachymeter may be a useful and accurate method in selected patients whose intraocular pressure measurement does not correlate with other clinical findings.