Vision Facts...
-Why is it harder to see things at near now that I am nearing 40 years old?
Things are BLURRY when I try to take out that splinter or thread that needle!
The way the eye is designed to focus at near depends upon the FLEXIBILITY of the LENS in the eye, NOT the muscle strength.
The focus of the crystalline lens inside the eye is controlled by the circular muscles around it. When those muscles RELAX the lens is stretched tightly, becomes thinner, and the average person can see far away. When the muscles WORK, they ALLOW the lens to 'free-float' without tension and thicken. The thicker shape creates a stronger NEAR power like a magnifying glass... thick in the middle and thin on the edges. Then to see FAR away again, the circular muscles around the lens RELAX, STRETCHING the lens thinner, making it a lower power to see far away.
Thus, it is the FLEXIBILITY of the lens that allows us to focus at near, NOT muscle strength. In fact, the muscles can contract throughout our entire life, even when the lens has NO flexibility remaining at all.
So, WHY IS IT HARDER TO SEE AT NEAR WHEN APPROACHING 40 YEARS OLD? Before birth the lens in the eye has its own blood supply from an artery and vein that extends from the optic nerve at the back of the eye, all of the way to the lens at the front of the eye. At birth, or just before, those vessels close and degenerate (leaving some 'floaters' that usually slowly disappear) and leaves the lens in the front of the eye with NO BLOOD SUPPLY. The lens cells start to die, and during our lifetime, and the lens itself progressively hardens until it cannot flex to change shape anymore, becoming a fixed lens power. This process starts at birth, and becomes noticeably bothersome for most people around 38 to 40 years of age while they wear their best distance correction.
At that age, we start to notice some near focusing effort when trying to focus on small near details, or when after focusing at near for awhile, there is a delay changing focus from near back to the far distance. For most people who are neither nearsighted or farsighted, this starts to become noticeable around the 38 to 40 year old period and is progressively worse until 60 years old, when people cannot focus at near with whatever best corrects their distance vision. This is the way the eyes are supposed to work. If that distance need is NO correction it is called EMMETROPIA . If emmetropes don't use the proper near correction in the 45 to 55 year old range, they put themselves at risk of losing DISTANCE CLARITY.
During this normal aging process, NEARSIGHTED people can many times remove their distance correction and still see at near longer than the 38 to 40 year old estimate. FARSIGHTED people will usually need a near correction sooner than the 38 to 40 year estimate. Regardless of what your correction need, this lens hardening process CANNOT be prevented.