Prescription Bell Curve?

[sdgibbs]

So looking at ordering a large quantity of finished lenses to have on hand, I thought i'd look up a bell curve of average prescriptions and to my surprise I couldn't find one. I remember seeing something like 65% of prescriptions are between +2 -2 and 95% are between +4 -4 (cyl not mentioned but this would be a good starting point) but I can't find that exact article either. Does anyone happen to know where I could find something like this? Thank you for any advice

[Barry Santini]

You'll need:

Few 0.25 cyl
Double 0.50 cyl
More minus than plus
Use aspheric plus for stk

B

[Uilleann]

Ask any lab - they should be able to give you info related to the powers they see every day. Often, stocks tend to run in powers similar to: +/-6 and up to 2 cyl. Some go more, some less. Some stock more cyl. Some stock less plus. Agree with Barry 100% - aspheric for the plusses.

[sdgibbs]

Sounds good thanks for the tips

This is an approx list of minus powers I threw together

http://i.imgur.com/QR8fxzh.png

[MikeAurelius]

Same thing with add powers on bifocals/progressives 60% between 1.25 and 2.25.

Check with one of the lens manufacturers for more details on that.

[HarryChiling]

So looking at ordering a large quantity of finished lenses to have on hand, I thought i'd look up a bell curve of average prescriptions and to my surprise I couldn't find one. I remember seeing something like 65% of prescriptions are between +2 -2 and 95% are between +4 -4 (cyl not mentioned but this would be a good starting point) but I can't find that exact article either. Does anyone happen to know where I could find something like this? Thank you for any advice

That was in an article / white paper on trilogy trivex lenses. Check younger site.

[LENNY]

First thing to consider is your patient base! Young old have money Medicaid... That will affect your usage quite a bit!

[Don Gilman]

Questions
1. What material are you going to order?
2. I assume cyls down the left side and sphs along the top? If so ordering to 4.00 cyl not wise. There will be a high extra charge for stock over a 2.00 cyl and you will be sitting on them forever.
3. PM me or regular E-mail and I will forward a matrix of what we sold in the past month. don@superoptical.com

[Dr. Bill Stacy]

I may increase my little stock of uncut finished lenses so I queried my database and have a report that shows all the single vision lenses run through my system so far. After removing all spheres above +6 and below -6, the total number dropped from some 21K Rxs down to around 16K. My printout is in PDF so I can't post that here. Anyone who wants a copy and can read PDF files, send me a private message with your e-mail and I'll send the report; it's 8 pages long and for me a real eye-opener, excuse the expression. When I get around to distilling it down to an actual order, I'll post that order here.

Your mileage may vary.

[Dr. Bill Stacy]

Oh and on the aspheric recommendation, I'm not a fan of aspherics, especially +. The powers near the edges of the lenses are often way different than the Rx sometimes making those areas unusable. They may have less spherical aberrations in those areas, but if the Rx itself is way off out there, why pay extra for a detuned lens? Kind of like multifocal IOLs and multifocal soft lenses...

[optical24/7]

Oh and on the aspheric recommendation, I'm not a fan of aspherics, especially +. The powers near the edges of the lenses are often way different than the Rx sometimes making those areas unusable. They may have less spherical aberrations in those areas, but if the Rx itself is way off out there, why pay extra for a detuned lens? Kind of like multifocal IOLs and multifocal soft lenses...

Doc, asphericity/atroicity improves optics peripherally. It not just to make a lens thinner. Expensive camera lenses aren't made aspherical to look thinner.

[Dr. Bill Stacy]

I know, but unlike a camera lens, in glasses often the line of sight is directed toward the edge of the lens, esp when reading. The camera lens equivalent to line of sight ALWAYS is coincident with the optical and physical center of the lens system. I'll always remember making a pair of glasses for my grand-daughter, ordered Zeiss Pure coat poly aspherics for her. The Rx called for something like +1.00 and they were +1.00 in the center, and nearly PLANO in the periphery. Haven't ordered any Zeiss aspherics since.

Unintended consequences.

Higher price not always=higher quality in ophthalmic lenses, including IOLs

[Robert Martellaro]

Oh and on the aspheric recommendation, I'm not a fan of aspherics, especially +. The powers near the edges of the lenses are often way different than the Rx sometimes making those areas unusable. They may have less spherical aberrations in those areas, but if the Rx itself is way off out there, why pay extra for a detuned lens? Kind of like multifocal IOLs and multifocal soft lenses...

That's only true for lens surface designs that use too much asphericity primarily to reduce center or edge thickness, much more than what is called for when using a flatter than best form base curve. For example, some of the old aphakic lenses, and on some of the newer minus lenses, using a free-form generator to over-aspherize the back side of the lens solely to reduce the edge thickness with no regards to the off-axis vision.

[Craig]

Do you really do that much same day that just getting them the next day doesn't work for you? I would keep very small and just order what you need for tomorrow.

[Chris Ryser]

My printout is in PDF so I can't post that here. Anyone who wants a copy and can read PDF files, send me a private message with your e-mail and I'll send the report;


.

If you scan a PDF document and save it as JPG picture you can post it here without any problem. I did learn the hard way by experimenting.

[sharpstick777]

Its true as Robert mentioned that there is a great difference between Aspheric designs between brands. We have tested most and found Seiko stock lenses with their patented MX aspheric design to as good as, or even better than, some digital SV free-form and non-aspheric lenses patient satisfaction. We do have a 20% central and east Asian population so that may skew the results a bit.

However, I always recommend Asph lenses over a -3.00 or +1.50/+2.00 because almost no one uses true form base curves, they are too steep in plus powers. Your best bet today is Aspherics for both better optics and cosmetics.

[sharpstick777]

your own bell curve will vary by area and materials, here in the Northwest we sell hardly any Poly because of its poor Abbe. However, they love Poly in California. Very few High Index will be needed in low powers. Also here, almost all our cyl is at -.50 and -.75, at -1.00 it drops off dramatically.

[Tallboy]

Question:

I stock spherical poly up to -3.00 and +2.00, with up to -1 cyl. This is mostly for emergencies or young'uns whose parents appreciate the convience.

I've thought about using aspherics, especially in plus. For those people with a minus OD plus OS lens situation - it would be in bad form to use an aspheric lens for the plus eye and non-aspheric lens for the minus eye, right?

[Dr. Bill Stacy]

I would object to mixing lens types in general, but I'm sure there are MANY cases where it would be ok. I'll defer to the proponents of aspherics to chime in here...