Question regarding lens thickness and Eye Size

[DrNeyecare]

Sorry if this is confusing. I"m confused just rereading it!!!

Patient w/ RX:
+5.50 -2.50 X 180
+5.50 -2.50 X 180
+2.25 add

She wants the best progressive we can offer her in the thinnest material.
Our office works with Hoya, so we ordered her the Hoya ID 1.67 Hi-Index

During the frame selection process, patient kept telling us that her last optical shop specifically told her that she must order glasses with eye size 46 or less in order to keep the thichness down. She told us that after size 46, the lenses for her prescription would be noticeably thicker.
Her current glasses is a rimlon metal 46-20-135 B:33. Its a typical plain metal women's frame.

I assumed what she meant was blank size, and normally with the labs we use, if the eye size is over 58, we get charged for oversize. So we fitted her with a more attractive frame of 50-17-135
We tried to get the sum of the eye and dbl to be as close as possible (46-20 vs 50-17) so that its a similar fit.

Upon arrival, her new Hoya ID Progressives did appear to look thicker and she got really mad at us. We looked around the show room again, but cannot find any frames with similar dimensions as her old ones (A:46 B:33 DBL: 20).
We offered to look thru our catalogs and find some rim-lons with the exact dimensions.

Unfortunately, the vendors we use don't have frames of these dimensions....

The closest I can find is a 48-19 B:33

Would this frame of A:48 be close in thickness to her A:46?

And is it true that A greater than 46 will be noticeably thicker?

[finefocus]

The thickness at the outer edge will be the same no matter what frame you select, but the inner edge and center will increase as the square of the radius. Not all 46's or 48's are created equal, use the ED instead of the A to calculate center thickness. With plus lenses, a small B will actually produce thicker-looking lenses: a deeper shape will allow the thickness taper away. You didn't say which part of the lenses were too thick, but the top and bottom are likely candidates. Outer edge will be thin, and the center wouldn't be that much different (Opticampus or Hoya can give you an exact number) from before, assuming similar Rx. Upgrade to 1.70, stretch the B, get the thinnest outer edge your lab will risk, and recognize that you've done all you can do.

[scriptfiller]

I'd be curious to know what her PD is for decentration purposes. I've done many a job with comparable RX in larger than a 50 eye and have had very pleasing results even using something like a 1.60. Me thinks decentration for PD is the key with this one.

[Spexvet]

For the thinnest temporal lens edge, make sure that the A plus DBL is not greater than the patient's PD. Rounder shapes will make the lower temporal edge thinner. Ideally, A plus DBL = PD in a round frame will give a uniform edge thickness along the entire circumfrence of the lens. And use 1.74 index - it's the thinnest material.

[Spexvet]

The Picasso masterpiece below is a top view of eyes/nose/glasses. The two parallel vertical lines represent the optical axes (PDs). The red vertical lines represent the edge thickness of a 46 eye, the green lines the thickness of a 50 eye. Not drawn to scale.

[DrNeyecare]

The Picasso masterpiece below is a top view of eyes/nose/glasses. The two parallel vertical lines represent the optical axes (PDs). The red vertical lines represent the edge thickness of a 46 eye, the green lines the thickness of a 50 eye. Not drawn to scale.

Spexvet: is this your own creation? or is this published material?
Maybe this is why the patient was passionate about only getting a 46 eye. As I mentioned before, her last optician told her that a 46 eye will give her the thinnest lens thickness for her prescription.

[Spexvet]

Spexvet: is this your own creation? or is this published material?
...

That is my own work.

[sharpstick777]

Please take the calipers to the lenses you received and measure the thinnest outside edge. It should be less than 2mm thick, but ideally it should be 1.2 mm. Often digitally processed lenses will come out thicker in pluses because the calculations are not designed to get knife edges, its designed to keep the cutting tool from hitting the block. If its not 1.4 discuss the issue with your lab to see if they can fudge the paramaters to get it thinner (lie to that computer I tell you). or switch to an ECP.

Switching from a 1.67 to 1.74 will save at most .6 mm in that RX and hoya does not offer 1.74.

Frame choice is the most important criteria in plus lenses, aspheric is second, material is third. You want her eye dead center in that lens, and the frame as round as possilble (tea cup shape is a good alternative). Adding 2 millimeters to the A increases thickness at the nasal quickly. With plusses I always dot the eye in the new and old frames, and measure the farthest distance to the edge of the frame. Its that distance that will determine how thick the lenses are plus the RX power. Reduce that distance as much as possible; shape, pd, bridge width, nose pad placement, and bridge height all play a role.

Also remember that most labs finish plus powers with a lens edge set on center as standard, which means half the lens always sticks out. Switching to a slightly higher base curve frame can help reduce this a bit if you request the lab edge on the front of the lens, but this often restricted by the frame. I have bent a few eyewires by hand to get a higher base eyewire and requested that the lab use the Z- measurement to bevel thereby matching the frame curve.

For small frames, you might try Jones NY Petites, Guess, OGI, Mezzini, and Jalapenos. I had a practice full of pin heads at one time.

It often takes a combination of techiques all providing a small level of improvement to acheive a good result.

[Uilleann]

For high presbyopic Rx's we have used the G. Armani GA 521 with great success. It's a 42-21 with a B of 33. Small, round-ish (teacup would be closer to the mark), stainless steel and will fit a variety of heads. Also comes in a 40-21 with a 31.5 B. I would agree that frame selection is critical here to begin with. If you're using Hoya, you may wish to try the 1.71 material, though as previously mentioned you won't gain a ton on thinness. Also, check with the lab and see that they're doing all they can do to maximize the asphericity of the lens. This is a corner that is sometimes cut...and one that may help you reach your target.

Let us know how you fare ok?

Bri~

[obxeyeguy]

The Picasso masterpiece below is a top view of eyes/nose/glasses. The two parallel vertical lines represent the optical axes (PDs). The red vertical lines represent the edge thickness of a 46 eye, the green lines the thickness of a 50 eye. Not drawn to scale.

Er, that's a minus lens. The lady in question is a plus 5.50, so center thickness is relavent, not edge.;)

[chip anderson]

You make the frame very much off the patient's PD and the center thickness is going to be a function of the edge. Not to mention one edge is going to be rather thick compared to the opposing edge.
Of course one could concider a lenticular or aspheric lenticular to get by with a little fudging on frame size.

Chip

[Spexvet]

Er, that's a minus lens. The lady in question is a plus 5.50, so center thickness is relavent, not edge.;)

D'oh!

So it's exactly what I said, but in reverse. :hammer:

[jefe]

It's often the B dimension that creates the appearance of excessive thickness. For creating a thin lens, the ideal frame would be one with a small round lens with no decentration either horizontally or vertically. When the OC on a plus lens is decentered upward, the lens looks very thick to the customer when she looks at the top. The center thickness of the 48-19 frame may not be much thicker than with the 46-20, but if the OC is higher because the frame sits low, the impression is created that the lens is thick.

As others have stated, the frame selection is more important in keeping the lens thin than the lens material. Keep the frame small and minimize decentration.

[DragonLensmanWV]

Sorry if this is confusing. I"m confused just rereading it!!!

Patient w/ RX:
+5.50 -2.50 X 180
+5.50 -2.50 X 180
+2.25 add

She wants the best progressive we can offer her in the thinnest material.
Our office works with Hoya, so we ordered her the Hoya ID 1.67 Hi-Index

During the frame selection process, patient kept telling us that her last optical shop specifically told her that she must order glasses with eye size 46 or less in order to keep the thichness down. She told us that after size 46, the lenses for her prescription would be noticeably thicker.
Her current glasses is a rimlon metal 46-20-135 B:33. Its a typical plain metal women's frame.

I assumed what she meant was blank size, and normally with the labs we use, if the eye size is over 58, we get charged for oversize. So we fitted her with a more attractive frame of 50-17-135
We tried to get the sum of the eye and dbl to be as close as possible (46-20 vs 50-17) so that its a similar fit.

Upon arrival, her new Hoya ID Progressives did appear to look thicker and she got really mad at us. We looked around the show room again, but cannot find any frames with similar dimensions as her old ones (A:46 B:33 DBL: 20).
We offered to look thru our catalogs and find some rim-lons with the exact dimensions.

Unfortunately, the vendors we use don't have frames of these dimensions....

The closest I can find is a 48-19 B:33

Would this frame of A:48 be close in thickness to her A:46?

And is it true that A greater than 46 will be noticeably thicker?

First thing is to get her out of the rimlon frames where they have to have a thicker edge than normal to make room for the groove. Go with all metal.