Presbyopia describes a progressive, age-related loss of the eye’s ability to adjust for near vision through accommodation.
The natural human lens is responsible for accommodation, i.e. switching between near and distance vision.
It is made from a flexible mass, the curvature of which is regulated by tiny muscles. As we age, the elasticity of the natural lens slowly but surely reduces. The eye therefore loses its ability to accommodate.
The natural lens can no longer perfectly adjust its refractive power. This loss of refractive ability means that a clear image can no longer be projected onto the retina when looking at an object close up. There is no clear focal point.
The lens’ curvature has to be able to change in order to see, particularly close up. Therefore, an increasingly rigid lens means that people become long-sighted over time.
Everyday activities such as reading or working at a computer become harder and harder. When reading, you will have to hold the book, newspaper or menu far away from your eyes to see it clearly... and shopping is almost impossible without glasses thanks to the miniscule text on most food packaging.