Answer: yes
Sudden blindness (total or near-total vision loss) in one eye is a medical emergency. In many instances, you have a short window of time for diagnosis and treatment to avoid permanent blindness. Temporary loss of vision may also be a warning sign of a serious problem, such as stroke
Explanation:
According to Scientific American.org, "Consider the case of a man known as GY. Damage to his visual cortex resulted in complete blindness in one half of the visual field. He could not consciously see anything, not even a spot of light, shown to him in that region. Yet when asked to reach out and touch the spot, he could do so accurately; he could touch a spot he couldn’t see! It seems downright spooky, but, as you will soon learn, we can explain—at least partially—his condition, known as blindsight, in terms of the multiple specialized anatomical pathways devoted to vision that we mentioned earlier. [For more on blindsight, see 'Subconscious Sight,' by Susana Martinez-Conde; Scientific American Mind, April/May 2008.]"
