Horopter

The horopter is an imaginary curved surface in space where objects are seen by both eyes at the same position on their retinas, resulting in single, fused images. It represents the set of points that, when viewed binocularly, produce zero disparity—meaning no difference between what each eye sees. The horopter's shape depends on how our eyes are positioned and is important for depth perception, allowing us to judge distances accurately. Essentially, it is a map of points in space where objects are seen without any conflicting images, helping our brain interpret the three-dimensional world.