What characterizes aniseikonia?

Aniseikonia is characterized by significant differences in the size or shape of images perceived by each eye. This condition can result in visual discomfort, binocular rivalry, and difficulties with depth perception. It occurs when the brain receives two dissimilar images from the two eyes, causing a disorienting experience for the individual. This could be caused by various factors, such as differences in refractive error between the eyes or aniseikonic lenses.

The other options do not accurately describe aniseikonia. The normal size of retinal images in both eyes reflects a condition where no significant disparity exists, which contradicts the definition of aniseikonia. Loss of vision without any disease in the eye does not pertain to image size or shape, and difficulty viewing objects up close relates more to presbyopia or other refractive conditions rather than directly addressing the unique characteristics of aniseikonia.