View Single Post
  #31  
Old 18-09-2019, 03:42 PM
Stonius's Avatar
Stonius (Markus)
Registered User

Stonius is offline
 
Join Date: Mar 2015
Location: Melbourne
Posts: 1,495
Quote:
Originally Posted by Don Pensack View Post
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.

I had heard that, but I thought that was to do with the eye's ability to focus *in general*.


I thought field curvature was more about a focal plane that is curved. Achieving sharp focus for the middle makes the outside go out of focus, and vice versa. So I'm thinking that as long as your eye can achieve focus at all, curvature should be just as much of a problem at any age, shouldn't it? Unless the shape of your retina (ie; the focal plane of the eye itself) changes with age?


Cheers


Markus
Reply With Quote