How does the visual system adapt to changes in light levels?

The visual system's ability to adapt to changes in light levels is fundamentally due to a process called adaptation. This adaptation occurs through several mechanisms that allow our eyes to adjust to varying lighting conditions.

When exposed to bright light, photoreceptors in the retina decrease their sensitivity, preventing overstimulation, which is known as light adaptation. Conversely, in low-light conditions, the sensitivity of the photoreceptors increases, allowing us to see better in darkness—this is referred to as dark adaptation.

This process enables the visual system to maintain optimal functionality across a wide range of lighting conditions, ensuring that we can see clearly whether in bright sunlight or dim environments. Other factors, such as pupil size adjustments and changes in lens curvature, also contribute to visual adaptation but are components of the overall adaptive process rather than the primary mechanism itself.