An optical coherence tomography (OCT) image of the anterior chamber of an eye is processed to determine automatically a location in the image corresponding to Schwalbe's line. First, the method finds the location of the corneal endothelium. Then the method fits a model to the detected corneal endothelium. Then the method determines the location of Schwalbe's line based on the relationship between the detected corneal endothelium and the fitted model, such as where the detected corneal endothelium diverges most from the fitted model. The Schwalbe's line is used to obtain a numerical measure of the anterior chamber angle of the eye. The method can be used in a process for screening patients for glaucoma. In the case of patients found to be suffering from glaucoma, treatment can be performed.