As illumination increases, what happens to visual acuity?

As illumination increases, visual acuity improves. This is because brighter lighting enhances the ability of the photoreceptors in the retina—rods and cones—to detect the details of the visual field more effectively. Under well-lit conditions, the cones, which are responsible for color vision and high spatial acuity, function optimally. This leads to a clearer and sharper vision, allowing individuals to discern finer details.

In low light, the visibility of details diminishes, and the visual system relies more on the rods, which are less effective at providing sharp images compared to the cones. Enhanced illumination ensures that the visual system operates efficiently, thus increasing visual acuity. This phenomenon is particularly relevant in the context of tasks that require detailed perception, such as reading or any activity where clarity is paramount.