The power of accommodation of the eye, often referred to simply as “accommodation,” is the ability of the eye to adjust its focus on objects at different distances. This process allows us to see objects clearly, whether they are near or far away. Accommodation is a crucial aspect of vision and is controlled by the eye’s crystalline lens.
Here’s how accommodation works:
Lens Flexibility: The human eye’s crystalline lens is a clear, flexible structure located behind the iris (the colored part of the eye). The lens can change its shape to alter its focal length, which is the distance from the lens to the retina at the back of the eye.
Near Vision: When you look at a close object, such as a book or a smartphone, the ciliary muscles surrounding the lens contract. This causes the lens to become thicker and more curved, increasing its refractive power. This adjustment allows the eye to focus the incoming light rays from the near object onto the retina.
Far Vision: Conversely, when you shift your gaze to a distant object, the ciliary muscles relax, allowing the lens to become flatter and less curved. This reduces the lens’s refractive power, enabling the eye to focus on distant objects by adjusting the focal length.
Accommodation is an automatic and rapid process that occurs as you shift your focus between objects at varying distances. It allows you to see objects clearly whether they are close up or in the distance. However, as people age, the flexibility of the crystalline lens tends to decrease, which can lead to a reduced ability to accommodate, making it more challenging to focus on close objects. This condition is known as presbyopia and often necessitates the use of reading glasses or bifocal lenses to compensate for the loss of accommodation.