rx prism in aspheric lenses

[ragtop]

Can anyone help me locate literature regarding grinding Rx prism in aspheric lenses such as spectralite, or thin and lite? Thanks Tom

[Darryl Meister]

If you're looking for sag height charts or some other kind of surfacing data, you will need to contact the specific lens supplier. If you are asking whether you can surface prescribed prism in an aspheric lens, in most cases you can. However, prism for decentration is not advised.

Best regards,
Darryl

[chip anderson]

Won't matter the coating will come off in 11 months on spectralite anyway. Why use an aspheric lens when prism is involved?

Chip

[Darryl Meister]

Why not use an aspheric when prism is involved?

We've sold tens of thousands of Spectralite lenses over the past 20 years. If you've experienced consistent hard coating failures on your Spectralite lenses for some reason, I would recommend contacting your laboratory.

Best regards,
Darryl

[chip anderson]

Daryll:
I did contact them over and over again. Finally just stopped using Spectralite ever again. Every damn one had coating failure at almost exactly 11 months.
I still have oddles and gobs of coating failures on other lenses from my favorite Zeiss Lab, Cumberland. I actually prefer thier lenses optically, expecially individuals, but I now hesitate to use them even on my personal glasses.
While this isn't exactly coating failure, my present lenses are Zeiss Indivdual with bad marks on each at the top from using slit lamp and lensometer.
Chip

[Darryl Meister]

We haven't had any unusual coating issues with Spectralite in the 16 years that I've been working for the company, aside from an unrelated, short-lived issue associated with progressive lens markings. I cannot speak to your personal experience, but I can assure you that if the factory coating routinely fell off the lenses, we couldn't have continued selling them for 20 years, between the cost of replacing them (the coating has a warranty) and losing major accounts that did a lot of volume in Spectralite back in the glory days of mid-index lenses.

Are you actually talking about the front factory hard coating, or some coating applied by a separate laboratory, such as a back-side hard coating or an AR coating?

[chip anderson]

Front factory hard coating. Have often wondered if this material needed AR to keep the hard coat on.

Darryl if you don't want this aired in public, please feel free to E. Mail me.

Chip

[Darryl Meister]

Darryl if you don't want this aired in public, please feel free to E. Mail me

Well, like I said before, if the coating was routinely falling off thousands of Spectralite lenses, I imagine that it would have to be a widespread issue in the public already. Having worked in the Technical Services / Quality department at SOLA during the peak Spectralite years though, I can honestly say that I don't remember ever receiving your phone call! In any event, I will forward your comments along to the appropriate person in the Quality group.

Best regards,
Darryl

[chip anderson]

Darryl:

You didn't see it because I did all my complaining to the labs I was getting work from. Didn't know how to move up the food chain then.
For the most part I don't think complaints to local labs and frame reps actually get passed up the food chain.
Things may be changing as more and more of the local labs are not locally owned or managed anymore.

Chip

[Darryl Meister]

Didn't know how to move up the food chain then

Ah. All of the dispensing guides and laboratory materials had the toll free number for the Technical Services Hotline. Half the calls we took were from eyecare professionals, the other half were from labs. If you repeatedly complained to your laboratory about this issue, and nothing was ever done, and given the low incidence of Spectralite hard coating failures over the past 16 years that I've been with the company, I wonder whether you were even getting genuine SOLA Spectralite lenses.

Best regards,
Darryl

[Quantrill]

So what are the pitfalls of using an aspheric lens when prism is involved?

[Darryl Meister]

So what are the pitfalls of using an aspheric lens when prism is involved?

I'm not aware of any pitfalls, although you must surface prescribed prism; you should not decenter to induce prism with aspheric lenses. Of course, when prescribing prism in spectacle lenses, in general, you should remain cognizant of factors such as lateral chromatic aberration and other aberrations; increased lens thickness and weight; and so on.

Best regards,
Darryl

[shanbaum]

I think you meant, "you should NOT decenter to induce prism..."

[Darryl Meister]

I think you meant, "you should NOT decenter to induce prism..."

Yes, good catch, thanks!