Can someone HELP me understand this thing?
Axis cross
Can someone HELP me understand this thing?
Buy a book and study.
Optical cross?
Perhaps someone can help us all understand this thing.... Axis Cross?
Axis cross
I am wondering how optical people do not know what this is, this is one of the basic requirements to sell glasses.Originally Posted by Clive Noble
You have your total powers of a lens.........spherical and cylindrical......and where they cross............there is the axis cross
Example in your lensometer: +100 sph +100 cyl at 90
first line at +100 at 180cross line at + 2.00 at 90or
first line at +2.00 at 90cross line -1.00 at 180
This can also be done without lensometer by visual neutralizing.
Last edited by Chris Ryser; 03-10-2006 at 11:27 AM.
Because there is no requirement to learn anything other than how to sell any longer. Opticians who do not know what an optical cross is simply cannot do their main task, which is Rx analysis and the transference of the data into a usable optical appliance. It never ceases to amaze me how continually fight the need for education in this industry.
Last edited by wmcdonald; 03-10-2006 at 10:29 AM.
Basic stuff...............
I guess this is the fault of using the automatic lensometers..........which means that one does not even have to know the basics.
I am also asking myself how one can check an RX coming back from the lab not having an idea aboy power and axis.
“It never ceases to amaze me how continually fight the need for education in this industry.“
And, even more amazing is the utter failure to improve the knowledge and standards of those who work in the industry. One would think that the optical schools in the US would have raised the licensing/registration bar higher and higher. It seems that the opposite has happened. Of course, when you run the figures and realize that less than 0.5 of all “opticians” have graduated from a formal, two year program it is no wonder that this is the case.
I have been retired now for a few years and no longer have the luxury of grabbing something off the board and ordering a pair of uncuts. So, I am now on the other side of the dispensing table and believe me, it pretty scary.
Thankfully, the originator of this post identified herself as an “optical sales person” and not an “optician.” I really don’t think that there are too many Opticians left out there. They are a dying breed.
She should of asked her Dad, he should know...he's an Optometrist.
Opticians education ...........................
On other thread last year........talking about professional education, it was strongly proposed that opticians need higher education than just an apprentiship.
I am now coming to a very strong conclusion................before even being let to serve a customer an optician should have a simply basic apprentiship of minimum a years or two, followed by an exam ......................and from then on get to a stepped up education.
Just think how all your large chains would suffer personal problems if at least half of their staff would not be allowed to work.
I would sure hate to see the day when students or novices are afraid to post questions on this site because the more experienced people disparage their lack of knowlege, lack of education ect. It wasn't a question about what an axis cross is, only a request to help understand it. Give her a break and answer her question. Maybe someday she'll be an expert and she can teach you something.
First, it is important to remember that the cylinder power of a lens is really the difference between the two major, or "principal," power meridians of the lens or prescription. These two power meridians, which are perpendicular to each other, represent the maximum and minimum powers of the lens or prescription.
To make an optical cross, the Sphere power is first placed on one leg of the cross, corresponding to the Axis of the prescription. The Axis is also noted on the leg of the cross. This is referred to as the axis meridian (or "sphere" meridian). The combined Sphere and Cylinder power (Sphere + Cylinder) is then placed on the leg of the cross at a right (90 degree) angle to the first leg. This angle (Axis +/- 90 degrees) is also noted on the cross. This is referred to as the power meridian (or "cylinder" meridian). These represent the principal meridian powers of the prescription. There is no Cylinder power along the axis meridian, while there is full Cylinder power along the power meridian.
Here is a graphic to illustrate how prescriptions are placed on an optical cross:
A prescription can be taken off an optical cross -- in minus cylinder form -- by first picking the meridian with the highest plus power or lowest minus power, and writing this power down as the Sphere power along with the corresponding Axis. The Cylinder power is then determined by subtracting the Sphere power from the remaining power meridian.
Darryl J. Meister, ABOM
I agree. If we are going to concern ourselves with the training level of the average optician, we should be equally willing to help raise that level when the opportunity presents itself. ;)
Darryl J. Meister, ABOM
It never ceases to amaze me how those who post the derogatory comments can neither spell properly nor string a simple sentence together.
I am unfamiliar with the term optical or axis cross, the above I would describe as the 'crossed cyl' method of displaying lens power.First, it is important to remember that the cylinder power of a lens is really the difference between the two major, or "principal," power meridians of the lens or prescription. These two power meridians, which are perpendicular to each other, represent the maximum and minimum powers of the lens or prescription.
To make an optical cross, the Sphere power is first placed on one leg of the cross, corresponding to the Axis of the prescription. The Axis is also noted on the leg of the cross. This is referred to as the axis meridian (or "sphere" meridian). The combined Sphere and Cylinder power (Sphere + Cylinder) is then placed on the leg of the cross at a right (90 degree) angle to the first leg. This angle (Axis +/- 90 degrees) is also noted on the cross. This is referred to as the power meridian (or "cylinder" meridian). These represent the principal meridian powers of the prescription. There is no Cylinder power along the axis meridian, while there is full Cylinder power along the power meridian.
Here is a graphic to illustrate how prescriptions are placed on an optical cross:
A prescription can be taken off an optical cross -- in minus cylinder form -- by first picking the meridian with the highest plus power or lowest minus power, and writing this power down as the Sphere power along with the corresponding Axis. The Cylinder power is then determined by subtracting the Sphere power from the remaining power meridian.
I guess there are many ways different people will state the same things.
hmmmmmmm.....
I have no idea why I am being so inclined to try to clarify things today, but this information could be useful so here it is...(Just being nerdy I guess)
Difficult to say rsandr, mainly because of where you live. But to a very large percentage of the optometric community here in the U.S. a cross cylinder would be a reference to the Jackson Cross Cylinder (JCC). The JCC is an actual lens and the part of a phoropter/refractor that is used to determine the strength and direction of astigmatism correction for a prescription. Hand held cross cylinders are also used (but less often) for refractions with a trial frame. A Jackson Cross Cylinder has a almost always has a specific power of +0.50-1.00 so that one meridian has a power of +0.50 and the other (90 degrees away) has a power of -0.50. In the U.S., I would encourage people to use the term optical cross in referrence to the information presented in Darryl's post to avoid confusion. It would be interesting to see if the terminology differs outside the U.S., let us know if you find this to be the case.
With that said, it hit me that the original post could have been (but probably not) a referrence to a JCC rather than the optical cross which was so well explained in Darryl's post.
As I understand it a 'cross cyl' is a piece of apparatus used in eye testing but 'crossed cyl' is a way of noting lens powers.I have no idea why I am being so inclined to try to clarify things today, but this information could be useful so here it is...
Difficult to say rsandr, mainly because of where you live. But to a very large percentage of the optometric community here in the U.S. a cross cylinder would be a reference to the Jackson Cross Cylinder (JCC). The JCC is an actual lens and the part of a phoropter/refractor that is used to determine the strength and direction of astigmatism correction for a prescription. Hand held cross cylinders are also used (but less often) for refractions with a trial frame. A Jackson Cross Cylinder has a almost always has a specific power of +0.50-1.00 so that one meridian has a power of +0.50 and the other (90 degrees away) has a power of -0.50. In the U.S., I would encourage people to use the term optical cross in referrence to the information presented in Darryl's post to avoid confusion. It would be interesting to see if the terminology differs outside the U.S., let us know if you find this to be the case.
With that said, it hit me that the original post could have been (but probably not) a referrence to a JCC rather than the optical cross which was so well explained in Darryl's post.
Cross cylinder has long been a tool used for laying out lenses for grinding in the lab especially back in the days when one "rocked in " a cylinder using spherical tools only. Also used to configuring toric and bitoric contact lens fits and powers.
Will often make complicated problems in contact lens configuration relatively simple to understand.
Chip
And if we keep on babying folks, they will not realize the ridulous nature of their questions. I have as much right to comment as these folks do to ask questions, I think but if not, maybe a board for experienced folks is in order?
I'm glad you see it as your place to ridicule.
Since it seems unclear as to what the original poster was asking, it is innapropriate to ridicule.
I think a good barometer would be to run some searches through your favorite internet search engine and see what you come up with. Whatever you would like to call it is fine with me, but I still encourage people to use the term optical cross for the process of diagraming and visualizing what powers are at what meridian in a lens.
Well I have just looked in Mo Jalies Principles of Ophthalmic Lenses and he seems happy.
Excuse me, my dad has been gone for over 12years. PLEASE DO NOT APOLOGIZE>I would LOVE to ask him.
I know what it is! I just have a time understanding how to put it to use. I know what it is meant to do. That's why I came to you guys to ask. I thought this was what this forum was for, was to help others in the business.
Maybe I did not use the correct term, please excuse me. As I said, I thought this was a place to exchange information. When I have read the other threads it seems like there are simpler questions asked. Answered that even stupid me knows.
Thank You to those that chosed to help. I am very grateful
Last edited by Karenrp1956; 03-10-2006 at 04:41 PM.
Here is what I just don't understand. A person asks a question and yes they should know it but for some reason they don't, we have all been there. The response is always the same all of the 'older' more 'experienced' opticians begin to complain about the state of opticianry today. They can go on and on and on and never once answer the question! Yes there should be standard education for opticians but guess what...THERE IS NO SUCH THING!!!! So do we nit pick a person who is attempting to learn? We need opticians to ask questions even if they are stupid ones. When opticians stop asking questions that means they are not learning. And opticians are not a dying breed! I know for a fact that there are many, many brilliant 'young' opticians out there and there is no short supply of 'older' opticians that do what they want and explain to us whipper snappers that 'I've been doin' this since you were in diapers' and yet never actually explain a darn thing!
All I have to say to you karenrp1956 is keep learning and ignore ANY ONE who wants to make you feel bad for not knowing what they know!
And we should all take a cue from Darryl and just answer the question!! Do you guys really think that you are in any way contributing to this field by not sharing information?
There are currently 1 users browsing this thread. (0 members and 1 guests)
Posting Permissions
Reply With Quote
Bookmarks