Assessment of paracentral stereopsis using a new method with the binocular open perimeter in patients with glaucoma

To investigate paracentral stereopsis in glaucoma patients with localized visual field (VF) defects using a novel assessment method.

A pilot study METHODS: Three glaucoma patients had an absolute scotoma (0 dB) in the superior visual field of one eye, with preserved inferior VF sensitivity bilaterally. Best-corrected visual acuity was ≥1.2 (≤-0.1 logMAR) and stereopsis was ≤120 arcseconds on a random dot stereograms (RDSs) test, without manifest strabismus. Paracentral stereopsis thresholds were measured using the Stereo Eccentricity Analysis (SEA) program implemented in the binocular open field imaging system imovifa^@. Seventeen test points within the central 15° VF locations, including the fovea, were tested with circular stereoscopic stimuli (200-3000 arcsec disparity) on a RDSs background for 500 ms, with size adjusted by eccentricity.

The mean binocular sensitivity for the superior field with a 0 dB scotoma was comparable to the monocular sensitivity for the superior field of the normal eye. Despite the preserved binocular sensitivity, however, paracentral stereopsis could not be confirmed in the affected superior field. In the normal inferior fields of the two eyes, paracentral stereopsis was detected, and higher stereopsis thresholds were observed with increasing eccentricities. These results were observed in all three cases.

In glaucoma patients, paracentral stereopsis was absent in the corresponding area of the VF defect regardless of the preserved binocular sensitivity. Its assessment may contribute to providing insight into functional vision loss beyond central stereopsis.