The focal length of the human eye when focusing closely can vary between 17-19 mm. This means that when the eye is focusing on objects that are close, the distance between the lens and the retina is around 17-19 mm.
The focal length of the human eye can be calculated by dividing the distance between the lens and the retina by the power of the lens. The power of the lens is measured in diopters.
Yes, the focal length of the human eye can change with age. As we get older, the lens of the eye becomes less flexible, which can affect the focal length and lead to presbyopia, a condition where it becomes difficult to focus on close objects.
Yes, the focal length of the human eye can be affected by external factors such as the shape of the cornea, the thickness of the lens, and the condition of the eye muscles.
Knowing the focal length of the human eye is important for understanding how the eye focuses on objects at different distances. It can also help in diagnosing and treating vision problems, such as nearsightedness or farsightedness.