I have a patient that has come in looking for a new pair of glasses. He is concerned with the thickness of the lens. Thus a 1.74 Essilor will be used.
His script is a -8 with a +1.5 and a PD of 62.
The two frames he has narrowed down to are:
Martin & Martin - Tom (50x16), No ED is spec'd
OGI - 7132 (50x18), ED of 52 is listed
Which of these frames produce a lens that is thinner for this specific patient.
What would the lens thickness be for each respective pair.
Originally Posted by mbiker
Go to www.opticampus.com and use the calculator for lens thickness.
Ah yes, I have attempted that but that does not take into account an ED.
Or does it?
Why not measure the frames ED yourself?
Would that not help you?
Are they that different?
Basic optics here.
Consumer?
I would if I had frames in hand, but I am not to that point yet. The consumer chose these based on other similar frames and catalog.
Results on both should be relatively equal. I can't imagine there being too great a difference in the ED in both cases.;)
Chris Beard
The State of Jefferson !
I'm a Medford man – Medford, Oregon. Up in Medford, we take our time making up our minds."
I'm just wondering why you would choose the 1.74 lens. For this Rx, there isn't much difference (less than .5mm edge thickness) between 1.6, 1.7, and 1.74. I would choose the lens that gives better vision over a lens that may be 1/2mm thinner that the patient will never notice without lens calipers.
A lack of planning on your part DOES NOT constitute an emergency on mine!
These are the lenses he has used in the past. His current pair has about three year old 1.74 Essilor's that the AR is flaking on. He has not had any problems with these lenses.
Ask him if he wants to see better than the 1.74. If so, get him 1.70. A barely noticeable difference in thickness, but a largely better ABBE value makes for a far more usable lens with lots less chromatic abberation.
Believe me, I was a minus 15,and when I got my first pair of 1.70 index lenses, I would NEVER use anything else for my high minus patients.
DragonlensmanWV N.A.O.L.
"There is nothing patriotic about hating your government or pretending you can hate your government but love your country."
?????
A lack of planning on your part DOES NOT constitute an emergency on mine!
But is it not the case that older ARs flake on any lens regardless of index? Also, the any problems of flaking was purely in regard to only the vision with the lens.
Anyways, back to the topic on hand. If you say there is only 0.5mm in difference between lenses, is the one that is discernable? He is considered with not only the thickness but also the fish bowl (facial cutoff at lens edge) effect a thicker lens brings. What are your opinions?
For the "fishbowl", be sure the lenses are small enough and close enough to not visually overlap the edge of the face. Regardless of the material, there will be a cutout if the outline of the face crosses the lens edge. Keep it small (I'm sure you will, anyway, for thickness control) and keep it close - reduce the vertex so the gap between face and lens is hard to see.
You could try a well-fit, well maintained RGP lens.
A lack of planning on your part DOES NOT constitute an emergency on mine!
The thinner lens will be the one with less decentration.
-8 with a +1.5 A 0
PD of 62.
Martin & Martin - Tom (50x16),
OGI - 7132 (50x18),
Thickness calculated with Box high of 25mm for both frames @n1.74.
Results see jpg
Last edited by Rafael; 12-02-2009 at 06:49 PM.
Dang-it Chip! Stop checkin' in under Bob's name and password! :finger:
:D:shiner::D!
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