Another reason I hate Slab's

[Mike Fretto]

I just want to make sure I understand how this will work, or better yet find out if it will work. Here goes CR39 st28

RX = OD +1.75 -3.50 X 093 with 4.50 BU

OS -1.50 -3.50 x090 with 4.50 BD

3.25 add eliminates Reverse unless Dr ok's 3.00 or 3.50

A=53.0 B= 38.0 seg height = 15.0 OC 4 above

Reading drop of 9mm = 2.92 BU OS

Will the BD at distance in the OS cancel the BU at near for
the slab-off????? I would think they are two seperate properties of the lense, at 4mm above the seg the patient will have 4.50 BD but I'm not sure I understand what effect the distant prism will have on the near prism.

[Mike Fretto]

Come on guys I need some input on this before the patient has the surgery on the other eye.

[Rich R]

Hello Mike, as far as I know the 9 degrees prism in the distance and near should stay the same, so going with 2.92 base up os is correct, all the slabs I've ever done never worried about what the distance prism is to figure amount of slab needed.
Rich R

[Jeff Trail]

Mike,

Rest easy my fellow lab ratican :-) You got it already, what you do to the distant in vertical placement (using prism) has nada with the slab. Since you are actually grinding as if it were two lens. Do the distant reblock and cut the slab...
One thing that should have been checked is the prism needed during convergence. You might have to do a little tinkering if if the imbalance is slightly different during convergence.
with that many problems as well as cats I would think thet the refracting OD should have no problem doing a little tinkering with the add.. depending on the BCA.
The way to go for ease of doing it as well as optical quality would be go with the molded slab.

Jeff "been there done that..and don't you hate just getting half the story on the order slips" Trail

P.S. remember the old days when you actually got the BCA on the order forms and knew when and where you could get by with tinkering. :-)