From: pcdhSpamMeSenseless@electrooptical.net   
      
   Jeroen Belleman wrote:   
   > On 2022-03-21 23:44, RichD wrote:   
   >> A person with normal vision will become far   
   >> sighted with age; his cornea loses the ability to   
   >> focus at close range.   
   >>   
   >> But a near sighted person will often retain   
   >> his close range vision, he doesn't need reading glasses.   
   >>   
   >> Can we explain this through optics?  Or is it really a   
   >> ophthalmology issue?   
   >>   
   >> --   
   >> Rich   
   >>   
   >   
   > At old age, a person will lose the ability to /change/   
   > focus. If he was near sighted to begin with, he will   
   > stay that way. The condition is called presbyopia.   
   >   
   > Jeroen Belleman   
   >   
   >   
      
   There's also a tendency for the resting focus to get further away, maybe   
   a diopter's worth, along with the reduction in accommodation. Mine sure   
   has.  I suppose that if your correction is -5 diopters when you're   
   young, having it go to -4 when you're old isn't that big a change. Going   
   from zero to +0.7 (age 62) is a bigger deal--I'm now on the edge of   
   needing glasses to drive.   
      
   Memorizing the eye chart is one of those useful things you can do while   
   waiting at the motor vehicles department. ;)   
      
   Cheers   
      
   Phil Hobbs   
      
   --   
   Dr Philip C D Hobbs   
   Principal Consultant   
   ElectroOptical Innovations LLC / Hobbs ElectroOptics   
   Optics, Electro-optics, Photonics, Analog Electronics   
   Briarcliff Manor NY 10510   
      
   http://electrooptical.net   
   http://hobbs-eo.com   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)