From: rlombardo3@gmail.com   
      
   Hi Peter,   
      
   The optical prescription is in diopters, which is the reciprocal of your   
   eye's focal point in meters.   
      
   For example, if your diopter is 2.75, then your EFL is 1 / 2.75 meters which   
   equals 0.36 meters = 14.3 inches.   
      
   As a test, close one eye and position your finger (or any text) at about 14   
   inches away and verify the image is at best focus.  Conversely, you can move   
   your finger back and forth in front of your eye until it is in best focus   
   and measure the distance.  Voila!, it will be about 14 inches.  Note: this   
   description is for myopia (near sightedness).   
      
    - Russ   
      
      
   "Peter Jason"  wrote in message   
   news:9apgq7pi7ecnftrbb4iolhhmassjkvdvct@4ax.com...   
   >I have progressive bifocals.   
   >   
   > I want to get spare glasses over the Internet, but   
   > separate readers and distance glasses.   
   >   
   > The prescription is:   
   >   
   > Right eye:   
   >   
   > Sphere +2.75   
   > Cyl -0.75   
   > Add 2.0   
   >   
   >   
   >   
   >   
   >   
   > Left eye:   
   >   
   > Sphere +3.00   
   > Cyl -1.25   
   > Add 2.00   
   >   
   >   
   >   
   > How do I specify readers & distance glasses from   
   > this data?   
   >   
   > Peter   
      
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