Best material for -13.00?

**ilanh** · 08-25-2011, 10:31 AM

We occasionally run into these very high myopes. We have easy access to 1.67 stock, otherwise it requires surfacing 1.70 or 1.74. I would be interested in finding out which way is most reasonable. The 1.67 stock is multiple times less costly than surfacing 1.74 but I don't want it to look too thick or be too heavy.

**DragonLensmanWV** · 08-25-2011, 10:45 AM

Do you want the best lens or the best price? The best lens is 1.70 because of it's superior ABBE value over 1.67 and 1.74 with very little difference in thickness. Remember, I used to be a -15 and ABBE really has a noticeable effect at those powers.

**ilanh** · 08-25-2011, 10:49 AM

I guess a better phrasing of my question would be: Does the sizeable difference in cost justify the improved performance? Or is it fairly similar?

**kcount** · 08-25-2011, 10:54 AM

@Ilanh Similar, go with the 1.67 and be done with it.

**DragonLensmanWV** · 08-25-2011, 10:56 AM

Do you want your patient to have the best possible vision? Or not?

**braheem24** · 08-25-2011, 11:19 AM

Sphere x Displacement / Abbe = Lateral Chromatic Abberation equivilancy in diopters.

ie. -10.00 x .15mm reading depth = 1.5D / Abbe 30 = 0.5D of abberation at 15mm from OC

or do Cr39 would be...

-10.00 x .15mm reading depth = 1.5D / Abbe 58 = 0.25D of abberation at 15mm away from OC

You know your patien's VAs, Can your patient differentiate?

**blinkvelo** · 08-25-2011, 11:48 AM

Originally Posted by DragonLensmanWV

Do you want your patient to have the best possible vision? Or not?

I personally think that that is the Patients decision on what is the best vision option they can afford or choose to spend. No one knows what a 'consumer' really values the most. Educate and let them decide. Also, YOu rlab can/should be able to tell you exactly what the thickness on the edge will be for a given frame/RX/Material. Just call and ask.

**kcount** · 08-25-2011, 11:52 AM

Originally Posted by blinkvelo

I personally think that that is the Patients decision ....

Are you kidding me! It's your job to present the best solution to the patient. Not go through 100 options and end up sounding like a used car salesman. Do you go to your GP and hear them asking patients what kind of medications they want to take? No, of course not the Dr. is a professional and takes command of the situation. Your not here to show the options, your here to show solutions. Patients are coming to you and seeking your advice. Be The Professional.

**TLG** · 08-25-2011, 12:40 PM

Originally Posted by DragonLensmanWV

Remember, I used to be a -15 and ABBE really has a noticeable effect at those powers.

Straight from the horses mouth. I have no idea what its like to be -13.00. But Dragon does. I'd listen up...

**Speed** · 08-25-2011, 12:48 PM

I'd try to find a supermodular. It's CR 39 but does more with curves than you can do with the index. I have made some beautiful glasses with those.

**braheem24** · 08-25-2011, 12:53 PM

Originally Posted by kcount

Do you go to your GP and hear them asking patients what kind of medications they want to take?

No, They go to the pharmacist and ask for a generic.

**Barry Santini** · 08-25-2011, 01:01 PM

My answer: 1.732 Zeiss Individual SV, made in Germany. Double aspheric.

Using this right now for a pair of -14.00's

Oh, and fully POW'd!

B

**DragonLensmanWV** · 08-25-2011, 01:09 PM

Originally Posted by Speed

I'd try to find a supermodular. It's CR 39 but does more with curves than you can do with the index. I have made some beautiful glasses with those.

It's a minus 13, not a plus 13.

**Speed** · 08-25-2011, 01:13 PM

Originally Posted by DragonLensmanWV

It's a minus 13, not a plus 13.

DUH. I just went to big trouble to break a pair of lenses!

**skt** · 08-25-2011, 01:42 PM

I have a good number of very high minue pts... I use 1.70

**blinkvelo** · 08-25-2011, 01:58 PM

Originally Posted by kcount

Are you kidding me! It's your job to present the best solution to the patient. Not go through 100 options and end up sounding like a used car salesman. Do you go to your GP and hear them asking patients what kind of medications they want to take? No, of course not the Dr. is a professional and takes command of the situation. Your not here to show the options, your here to show solutions. Patients are coming to you and seeking your advice. Be The Professional.

Being the Professional and giving the best advise is exactly what i think this profession should strive to do! Educate the patient and offer the best solution(s), Like two choices not 100. A poor and old school used "car salesman" will try to rial road a buyer into all the "extra" they don't need. That's why they're a dying breed. To few is as bad as to many.
I'm sure there are several thread that beat this topic like a dead horse. I'm sorry to ilanh for getting off the question to far.

**Elvis Is Alive** · 08-25-2011, 02:18 PM

I'd recommend 1.70 in most cases like this. Higher ABBE value (42) than 1.67 (32) or 1.74 (33). Keep in mind, you get significantly higher veiling glare and brighter ghost images as you increase the index of refraction. Highly recommend high quality AR with any of these materals for best performance.

Of course, frame selection is key with an rx like this. Smaller "A" measurement and round or oval shape work best. For those who want to calculate edge/center thickness, I find this useful:

http://www.opticampus.com/tools/thickness.php

Saves time from using that formula that I've long since forgotten for lens thickness.

**Barry Santini** · 08-25-2011, 05:41 PM

My only problem with the 1.70 lenses (all from Hoya) is that they ALL shed their AR over time...all of them!

B

**bob_f_aboc** · 08-25-2011, 07:29 PM

Barry, I have a pair of 5 year old 1.7 HOYA lenses with Super HiVision that, aside from some scratches, are in great condition with no sign of the AR coming off the lenses.

**DragonLensmanWV** · 08-26-2011, 06:22 AM

My old 1.70 Summit ECPs with SHV are now getting to be three or four years old and the AR is still good. Haven't been worn for quite some time now.

**I-Care** · 08-26-2011, 07:17 AM

Originally Posted by kcount

are you kidding me! It's your job to present the best solution to the patient. Not go through 100 options and end up sounding like a used car salesman. Do you go to your gp and hear them asking patients what kind of medications they want to take? No, of course not the dr. Is a professional and takes command of the situation. Your not here to show the options, your here to show solutions. Patients are coming to you and seeking your advice. Be the professional.

well said!

**jmchapman** · 08-26-2011, 08:14 AM

Originally Posted by braheem24

No, They go to the pharmacist and ask for a generic.

hahahaha zinger

**Robert Martellaro** · 08-29-2011, 12:18 PM

Originally Posted by Barry Santini

My only problem with the 1.70 lenses (all from Hoya) is that they ALL shed their AR over time...all of them!

B

I've also seen a high (estimate more than 20%) failure rate, mostly from 1.70 iD's ordered around 2006-2007. Most failed in the two warranty period, primarily from orange peel and crazing. Lenses all had very thin centers (.9mm to 1.1mm) which may have been a factor, but I've seen a few plus lenses fail also. It can be a problem when working with new materials and coatings, where accelerated wear testing doesn't uncover every possible manufacturing problem.

**sharpstick777** · 08-29-2011, 12:27 PM

There are finished 1.74's available in the that power if you look, it will save a lot of $. Patients have different priorities, if clarity is important go with 1.70, if cosmetics is most important go with 1.74. I would not recommend 1.67 unless the patient is trying to save money.