How does peripheral vision increase and decrease?

Peripheral vision can increase in sensitivity and range when a person is in low-light conditions or when focusing on a central object, as the eyes adapt to detect movement and shapes in the periphery. Factors such as fatigue, distractions, or eye strain can decrease peripheral vision, making it harder to notice objects outside the direct line of sight. Additionally, aging and certain eye conditions can also negatively impact peripheral vision. Overall, it is influenced by both environmental factors and physiological changes in the eyes.