Relationship between optic nerve head topography and nerve fiber layer thickness with central corneal thickness in patients with primary open-angle glaucoma

Abstract

Introduction/Objective. In patients with primary open-angle glaucoma (POAG) we explored the relationship between the optic nerve head (ONH) topography parameters and the retinal nerve fiber layer (RNFL) thickness with the central corneal thickness (CCT). Methods. This retrospective study included 97 patients (97 eyes) with primary open-angle glaucoma. Patients were divided into a thin CCT < 540 ?m (45 eyes) and a thick CCT ? 540 ?m (52 eyes) group, using ultrasonic pachymeter. Topographic measurements of the ONH parameters and RNFL thickness was performed using optical coherence tomography (OCT). The outcomes were compared with the thin and thick CCT and correlated with the thin CCT of the subjects. Results. There were significantly lower mean intraocular pressure (p < 0.0001) and CCT (p < 0.0001) in patients with thin CCT compared to patients with thick CCT. Statistically significant differences of ONH parameters were found in thin cornea group compared to thick cornea group in: cup/disc area ratio (p < 0.03), vertical cup/disc ratio (p < 0.01) and rim volume (p < 0.01). Statistically significant differences of RNFL thickness were found in thin cornea group compared to thick cornea group in: average (p < 0.001), superior (p < 0.03), inferior (p < 0.03) and nasal (p < 0.01). Significant positive correlation was found between thin CCT and OCT parameters in: optic disc area (r = 0.429, p = 0.003), cup/disc area ratio (r = 0.287, p = 0.05), horizontal cup/disc ratio (r = 0.472, p < 0.001), vertical cup/disc ratio (r = 0.578, p < 0.001), average RNFL (r = 0.796, p < 0.001), superior RNFL (r = 0.665, p < 0.001), inferior RNFL (r = 0.650, p < 0.001), nasal RNFL (r = 0.611, p < 0.001) and temporal RNFL thickness (r = 0.601, p < 0.001). Conclusion. POAG patients with thin cornea will probably develop larger glaucoma changes than those with a thicker cornea. Ultrasonic pachymetry measurements of CCT and OCT analysis of ONH topography parameters and RNFL thickness provide significant information in early diagnosis and monitoring progression of POAG.