Which term describes normal vision without refractive error?

The term that describes normal vision without refractive error is "emmetropia." This condition signifies that light rays entering the eye are focused directly on the retina, allowing for clear vision at various distances without the need for corrective lenses. Essentially, emmetropia represents the ideal state of vision where no adjustments are necessary, and it is an important baseline for understanding various refractive errors.

Myopia refers to nearsightedness, where distant objects appear blurry due to light being focused in front of the retina. Hyperopia, or farsightedness, occurs when distant objects are seen more clearly than close ones, because the light is focused behind the retina. Astigmatism is characterized by an irregular curvature of the cornea or lens, leading to distorted or blurred vision at all distances. Each of these conditions represents a deviation from emmetropia, highlighting its significance as the standard for normal visual function.