Comparing corneal variables in healthy subjects and patients with primary open-angle glaucoma.

PURPOSE: This study was designed to identify possible differences between healthy subjects and patients with primary open-angle glaucoma (POAG) in keratometry, central corneal thickness, overall corneal thickness, mean thickness of a circular zone centered at the corneal apex of 1-mm radius (zone I), and mean thickness of several concentric rings also centered at the apex of 1-mm width (zones II to VI, respectively). METHODS: These variables were recorded in 126 healthy subjects and 130 patients with POAG. Corneal thicknesses and the power of the flattest and steepest axes were compared between the two populations using a t-test and the position of the flattest axis using a Mann-Whitney U test. A binary logistic regression procedure was used to determine the diagnostic capacity of the corneal variables using the area under the receiver operator characteristic curve (AUC) to select the best regression equation. RESULTS: Significant differences between subjects and patients were detected in mean corneal thickness and in mean thicknesses of zones I to VI. The logistic regression model included as predictors the mean corneal thickness and the mean thicknesses of zones IV and VI; for this model, the AUC was 0.711, sensitivity was 67.7%, and specificity was 65.5%. CONCLUSIONS: Healthy subjects and glaucoma patients differ significantly in terms of mean overall corneal thickness and thicknesses of the corneal zones I to VI defined here. The variables mean corneal thickness and mean thicknesses of zones IV and VI are able to discriminate between subjects with or without glaucoma.

Localization of endothelin-1 mRNA expression and immunoreactivity in the anterior segment of human eye: expression of ETA and ETB receptors.

PURPOSE: Endothelin-1 (ET-1), a potent vasoactive peptide, is an important regulator of intraocular pressure. Actually, there is evidence of a role for ET-1 in the pathogenesis of glaucoma. However, the expression pattern of ET-1 and its receptors, ETA and ETB, in the anterior segment of human eye are not known. In the current study, we have examined the expression and distribution of ET-1 as well as the expression profile of ETA and ETB genes in the iris, ciliary muscle, and ciliary processes of human eyes. METHODS: Six normal human eyes with no history of eye diseases were fixed, embedded in paraffin and sectioned. Cellular localization of ET-1 was identified by in situ hybridization and immunohistochemistry. Iris, ciliary processes, and ciliary muscles were dissected from six normal human eyes and quantitative real time RT-PCR was used to quantify the expression of ETA and ETB. RESULTS: In situ hybridization revealed the presence of ET-1 transcripts in the iris, nonpigmented epithelial ciliary cells, and ciliary muscle. Immunohistochemical studies showed that ET-1-like immunoreactivity appeared in the same regions where ET-1 mRNA was expressed as well as in trabecular cells, inner and outer endothelial cells lining Schlemm's canal, corneal epithelial, and limbus cells. Quantitative real time RT-PCR demonstrated that the expression of ETA and ETB receptors is greatest in the iris, followed by ciliary muscle and ciliary processes. CONCLUSIONS: ET-1 and its receptors ETA and ETB are constitutively expressed in the anterior segment of human eye. These results indicate that ET-1 may play a physiological role in the regulation of intraocular pressure through its ETA and ETB receptors in human eye. In addition, ET-1 present in corneal epithelium and limbus may function in regulating cell proliferation and/or differentiation.