Corneal Elevation Topography in Primary Open Angle Glaucoma

The purpose of the study was to describe and compare anterior and posterior topographic elevation maps in primary open angle glaucoma patients with functional damage staging and in healthy controls.

A total of 217 subjects were consecutively recruited, including 111 primary open angle glaucoma patients (patients), and 106 healthy individuals (controls). All patients performed Pentacam HR corneal topography. Mean anterior keratometry and anterior and posterior topographic elevation maps were compared in the central 3, 5, and 7 mm. Humphrey automated perimetry results from the patient group were classified according to the Glaucoma Staging System.

Age (patients: 72.32±8.09; controls: 70.82±8.36; P=0.18) and central corneal pachymetry (patients: 541.13±36.98; controls: 548.67±34.56; P=0.12) were similar in both groups. Maximum elevation readings in the central 5 mm were significantly (P<0.05) higher in the anterior (patients: 8.21±8.63; controls: 5.79±3.62) and posterior (patients: 16.17±8.72; controls: 13.92±6.03) corneal topography of the glaucomatous patients, as well as in the anterior (patients: 17.32±20.78; controls: 9.61±5.64) and posterior (patients: 38.81±19.78; controls: 26.38±12.73) central 7 mm. There was a weak but significant correlation between the Glaucoma Staging System stage and both the anterior 5 mm (r=0.397) and 7 mm (r=0.304) maximum, as well as the posterior 5 mm (r=0.233) and 7 mm (r=0.241) maximum.

In patients with primary open angle glaucoma, there is a forward shifting of the posterior and anterior corneal surfaces. This appears to be correlated with more advanced stages of functional damage, pointing to a possible link between corneal structural changes and duration and intensity of elevated intraocular pressure. Further studies may ascertain the potential for this biological marker to be used in monitoring primary open angle glaucoma patients.