What is a common symptom of a refractive error?

Blurred vision is a common symptom of refractive errors, which occur when the shape of the eye prevents light from focusing directly on the retina. Conditions such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism can all lead to a blurring of vision at various distances. This is due to the eye's inability to properly refract (bend) light rays, resulting in images appearing unclear.

In contrast, while double vision, headaches, and night blindness can also be associated with various visual disorders and conditions, they are not characteristic symptoms of refractive errors specifically. Double vision often points to a misalignment of the eyes or issues with the eye muscles. Headaches can arise from eye strain or tension, which may be related to refractive errors but are not exclusively a symptom of them. Night blindness is typically linked to conditions affecting the retina or a deficiency in certain nutrients, rather than refractive issues. Therefore, the primary and most direct symptom associated with refractive errors is blurred vision.