Instead of seeing two different images or double vision (diplopia), the brain suppresses the blurrier image.
During the first few years of life, preferring one eye over the other may lead to poor visual development in the blurrier eye.
Because the brain cannot fuse the two images, the brain suppresses the blurrier image, causing the eye to become amblyopic.
Cataract. Clouding of the lens of the eye causes the image to be blurrier than the other eye.