Reduced peripheral vision in glaucoma and boundary extension.

Clinical Relevance: Peripheral vision is known to be critical for spatial navigation. However, visual cognition, which impacts peripheral vision, has not been studied extensively in glaucoma.

Background: Spatial memory was assessed with a known to induce a robust memory distortion called "boundary extension" in which participants erroneously remember seeing more of a scene than was present in the sensory input.

Methods: Fifteen patients with glaucoma and 15 age-matched normally sighted controls participated in the experiment. Participants were shown 10 photographs of natural scenes randomly displayed for 0.5 s or 10 s. Following each scene, the participant was asked to draw it from memory.

Results: On average, boundary extension was larger, by 12%, for patients than for controls, but the difference was significant for 4 photographs. Patients tended to add more space between the object and the edges than there was between the objects and the border of the photograph. A control experiment in which participants were asked to draw isolated objects without scene context resulted in a significant reduction of the memory distortion in both groups, but patients still drew the objects smaller than controls.

Conclusion: The reduced field of view in glaucoma has an impact on spatial memory for scenes and on perception of size.