The selective effects of elevated intraocular pressure on temporal resolution

Abstract

Twenty-seven eyes of 27 patients with normal tension glaucoma (NTG), 68 eyes of 68 patients with primary open-angle glaucoma (POAG), and 11 eyes of 11 patients with special forms of high-tension glaucoma (SHTG) including (pigmentary glaucoma, angle-closure glaucoma, secondary glaucoma, etc.), were examined by automated light-sense and temporal resolution perimetry. Light-sense perimetry was performed with the Humphrey Field Analyzer, using program 30-2. Temporal resolution perimetry was conducted with a system developed by Lachenmayr. Global field indices were calculated for all visual fields and modalities: mean defect (MD) for light-sense perimetry and mean flicker defect (FD) for flicker perimetry. For each of the three glaucoma groups there was a significant linear correlation of FD over MD. The slope of the regression line (regression coefficient a) increased with increasing maximal pressure level of the glaucomatous group: for NTG a = 0.6671, for POAG a = -1.2413, and for SHTG a = -2.235. The differences of the regression coefficients between NTG and POAG and between NTG and SHTG were statistically significant (P = 0.0366 and P = 0.0046, respectively). The results of the present study provide evidence that the relative amount of damage to flicker compared to light-sense perimetry increases with increasing maximal pressure level of a glaucomatous population. Thus, flicker perimetry may be a tool for the identification of eyes with pressure-produced damage.