Quote:
Originally Posted by Stonius
That's interesting - I wonder why that is?
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The lens of the eye not only yellows then turns brown as we age (UV damage), but also hardens so the muscles in the eye gradually grow less able to change the lens shape to accommodate for distance.
It starts with near vision first. At around 40 we need reading glasses. Then, 50 requires bi-focals and 60 trifocals and the near prescription strengthens.
Alas, the lenses don't "freeze" at infinity focus, but somewhere closer because we live indoors, so older individuals need a distance prescription too.
If UV damage gets severe enough,small opacities become apparent in spots in the lenses, which gradually progress toward a cloudy translucency to the lens. This is called cataracts and the mitigation of the effects requires a lens replacement--a common surgery.
Human trials start this year for a steroid-like substance which can dissolve cataracts. It worked in 98% of all mice so there is hope that lens replacement surgery may be a thing of the past in a few years.