The focal length of the human eye can vary slightly among individuals but is typically around approximately 22-24 millimeters. The focal length of the eye is determined by the shape and refractive properties of its various components, including the cornea and the crystalline lens.

The eye’s ability to focus on objects at different distances is a result of changing the shape of the crystalline lens. When you look at distant objects, the lens becomes thinner, and its focal length effectively becomes longer. When focusing on close objects, the lens becomes thicker, reducing its focal length. This process is known as accommodation.

It’s important to note that while the average focal length of the human eye falls within the range mentioned, individual variations can occur. Additionally, the eye’s ability to focus on objects at different distances is a dynamic process, and the eye can adjust its focal length to provide clear vision over a wide range of distances.