I was going to see if anyone could help explain this to me:
VisionMonday/May 16, 2005:
"Three Rivers Optical, a major independent wholesale lab bases here (Pittsburg), has developed a new bifocal lens with a unique combination of features. The lens, available exclusively from Three Rivers, joins a round-segmented design in polycarbonate with the latest photochromic technology from Transitions Optical, Transitions V with ESP. Three Rivers is marketing the lens under the brand name "TR O SEG."
later the article says:
"Steve Seibert said round seg bifocals offer several advantages over flat-top bifocal designs, such as a thinner, less noticeable ledge and not as much image jump."
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I was looking for someone to help explain how this round bifocal is different from the previous versions of round bifocals currently available. It has been my understanding that round bifocals have nearly 3 x more image jump than Flat Top Bifocals.
Example: Round 22 Plano +2.00 Add
Prism = F x dec (mm)/10
Prism = 2.00 x 11/10
Prism = 2.2 base down
Flat Top 22 Plano +2.00 Add
Prism = F x dec (mm)/10
Prism = 2.00 x 4/10
Prism = 0.8 base down
So I guess I am trying to figure out if Three Rivers reinvented the round bifocal or if perhaps a refresher course in Image Jump is needed.
Adam
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