Latent asymmetric intraocular pressure as a predictor of visual field defects.

OBJECTIVE To investigate the association of latent asymmetric intraocular pressure (IOP) (IOP asymmetry between fellow eyes when patients were in the supine position but not when sitting) with visual field (VF) defects in patients with open-angle glaucoma. METHODS Fifty-three patients with open-angle glaucoma, who were receiving the same topical medication in both eyes, were enrolled and were housed in a sleep laboratory for 24 hours. Intraocular pressures were measured when the patients with open-angle glaucoma were in the supine position or were sitting. A group of patients with latent asymmetric IOP was identified. Intraocular pressure asymmetry, monocular diurnal IOP fluctuation, and VF indexes were compared between the groups with and without latent asymmetric IOP. RESULTS Among the study population, 16 patients had latent asymmetric IOP. Compared with fellow eyes, their hypertensive eyes demonstrated greater IOP fluctuations in the sitting and supine positions and had more aggressive VF defects. In addition, the eyes in patients having latent symmetric IOP showed significantly greater diurnal IOP fluctuations in the sitting and supine positions and more severe VF defects compared with the eyes in patients having symmetric sitting and supine position IOPs. CONCLUSIONS Patients with latent asymmetric IOP are at increased risk of VF deterioration. Latent asymmetric IOP may be a predictor of glaucomatous VF defects. Further investigation in a larger, more diverse group of patients is needed to assess the diagnostic implications of latent asymmetric IOP relative to glaucoma therapy.