NBEO Visual Perception Practice Exam 2025 – All-in-One Guide to Exam Success!

Phosphenes are visual sensations that occur when the retinal cells are stimulated without light entering the eye. This stimulation can happen due to mechanical rubbing of the eyes, which physically compresses the eye and activates the photoreceptors or other retinal cells, leading to the perception of light flashes or patterns. The phenomenon can also be associated with neural noise, which is the random firing of neurons in the visual system.

This experience is commonly reported when individuals rub their eyes, resulting in various shapes or colors appearing in their vision, while there is actually no external light source present. The presence of phosphenes is a direct demonstration of how our visual system can interpret mechanical stimuli or spontaneous neural activity as visual information.

The other phenomena listed in the choices relate to different aspects of visual perception. For instance, the Purkinje tree involves the shadow cast by the blood vessels in the retina, Moore's Lightning streaks refer to a visual effect commonly associated with certain types of retinal stimulation, and blue arcs of the retina are perceptual effects experienced by some individuals but are not primarily caused by direct mechanical stimuli.