The corneal thickness profile in different forms of glaucoma

To characterize the corneal thickness profile in primary high pressure (HPG) and normal pressure (NPG) open-angle glaucoma as well as pseudoexfoliative glaucoma (PEXG), and to analyze the influence of possible causative factors. Glaucoma patients and healthy age-matched subjects were included. In glaucoma, disease duration, current medication, functional (Humphrey perimetry) and structural (Heidelberg retina tomography) damage, and endothelial cell density (ECD) were assessed. The spatially resolved corneal thickness was measured with Pentacam HR. Thinnest corneal thickness (TCT) and peripheral pachymetry of concentric circles around TCT were determined. The Scheimpflug Analyzer Corvis ST was used to measure central corneal thickness (CCT) and pachy slope, which is an indicator of the change in corneal thickness from the apex to the periphery. After age adjustment, 112 healthy subjects and 286 patients (161 HPG, 76 NPG, 49 PEXG) were included. In glaucoma, CCT, TCT and pachy slope were significantly reduced (P < 0.001). Likewise, peripheral pachymetry at various distances (P < 0.001) and the differences between TCT and periphery (P < 0.019) were lower than in healthy subjects. There were also significant deviations when analyzing the different forms of glaucoma (all group comparisons P < 0.001, with lower pachymetric values in each patient group compared to healthy controls). Furthermore, the changes were associated with parameters of structural damage (e.g. pachy slope and rim area, P < 0.001), disease duration (PAC 5 mm, P = 0.016) and use of prostaglandin analogues (e.g. CCT, pachy slope, PAC 5 mm, all P ≤ 0.05). Glaucoma involves corneal thinning, affecting not only the center but also the periphery. The physiological increase in peripheral corneal thickness was reduced in all glaucoma subgroups. The associations with influencing factors might indicate pathogenetic mechanisms.