Presbyopia, is not truly a refractive error, but is the natural
process of the eye losing the ability to accommodate or change
the shape of the natural crystalline lens inside the eye to
see comfortably at near.
Usually over the age of 40 this ability to see near objects
clear becomes less. The best information we have today regarding
the gradual loss of accommodation places blame on the lens
Unlike the rest of the body, which stops growing by the
age of twenty, the lens of the eye continues to grow throughout
life. As the lens ages and grows, it becomes harder in consistency
and, therefore, resistant to changes in shape.
The result is a gradual reduction in accommodation, and
a more dependence on reading glasses.