What are common symptoms of double vision?

Seeing two images of a single object is the defining characteristic of double vision, also known as diplopia. This symptom can occur when the eyes are not properly aligned, leading to the brain receiving multiple signals for what should be a single visual target. The phenomena of dual images can manifest in various ways, including horizontal or vertical diplopia, depending on the underlying cause, such as strabismus, cranial nerve palsies, or other neurological disorders.

While blurry vision, itchy eyes, and dryness can relate to various vision problems or eye conditions, they do not specifically indicate double vision. Blurry vision might occur in conditions like refractive errors or cataracts, itchy eyes are often associated with allergies or irritations, and dryness can lead to discomfort but does not provide the dual-image effect that defines double vision. Therefore, the clarity and specificity of seeing two images of a single object is what makes it the correct answer.