My patient's Rx is +7.50 +1.00 with a +2.25 add. He is wearing FT28 with a center thickness measuring 7mm. I am having a hard time finding the thinnest material available in this power. Would appreciate suggestions.
My patient's Rx is +7.50 +1.00 with a +2.25 add. He is wearing FT28 with a center thickness measuring 7mm. I am having a hard time finding the thinnest material available in this power. Would appreciate suggestions.
trivex and poly in their materials. 1.67 in itsOriginally Posted by Tucsontech
Be very careful............looking at the addition of 2.25 your patient seems to be over 60 years old.
At that age the patient has worn that distance RX for ever. By giving him or her a material that will be thinnrer you will also have to change the base curves which will produce a different picture perception.
Make sure patient knows about this and will be able to adapt to it.
Rodenstock do a FT28 1.67. most generic labs would be able to surface a non-branded FT28 in 1.67
There's not much to choose from at this power with a ST28 (in the US). The biggest problem is finding a steep enough base curve to keep the back curve concave. You have +8.50 on one meridian so you need a true BC of at least that much, maybe a little less if it's higher index, but the only 1.66 aspheric is made by Optima, and the steepest curve is listed at +7.00 with the true curve probably less than that. The "best form" BC for this Rx is probably +10.00, your best bet might be to use aspheric cr39. Bristol makes a lens like this, Rodenstock might still make the Cosmolit (my choice), not sure if the Aire-O-Lite is aspheric. If the off-axis vision can be compromised (that includes the reading) then you might try the Optima lens with a back surface convex grind (bi-convex), that's if you can find a lab who can do a bi-convex.
Regards,
Science is a way of trying not to fool yourself. - Richard P. Feynman
Experience is the hardest teacher. She gives the test before the lesson.
I've done a couple of pairs in Mid-Index over the past year or so, with similar scripts. They are a little thinner than conventional CR39, and AFAIK, there have been no adaptation issues. I used the X-Cel 1.555 D-28 and D-35 for these patients, the only problem I had was having to double-glove when deblocking them :shiner:
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