Page 1 of 2 12 LastLast
Results 1 to 25 of 34

Thread: 0.25 and axis tolerance question

  1. #1
    Rising Star Monkeysee's Avatar
    Join Date
    Oct 2004
    Location
    Canada
    Occupation
    Ophthalmic Technician
    Posts
    103

    Question 0.25 and axis tolerance question

    Hi, I am interested in finding out how different ECP's handle axis tolerance on 0.25 (and other) cyl's. Is the ANSI standard 5 or 7 degrees off axis to pass a 0.25 cyl Rx? I do finishing work for an OD who insists all axis, regardless of power, be within 2 degrees-he says the ANSI standards were just "made up" by Labs to save money on redo's?!! I find I have some success if I go to his office and dot up the single vision lenses for edging on his lensometer, (a Marco-the one with the prism dial), rather than dot them up on my Reichert 70 at the lab. I also verify the jobs when they are done on his Marco and adjust/twist lenses till the axis appears correct- even then his assistant will still reject jobs for being off axis! Its a pain! It drives our surfacing lab suppliers crazy too, but I won't even go there..........Any feedback would be great.
    Chimperial Optical-what a great place to work!

  2. #2
    since 1964 Homer's Avatar
    Join Date
    Jan 2001
    Location
    Estes Park, Colorado, usa
    Occupation
    Dispensing Optician
    Posts
    754

    The Doctor is out to lunch!

    Get another account to replace this one. As as any lab person will tell you and I'm sure you know, there is absolutely not consensus between doctors as to what the tolerances are ..... except perhaps the voluntary ANSI standards - which have become less tolerant in recent years.

    From both the lab side, isn't it interesting that the more tolerant doctors usually have a fairly good business and few customer complaints.

    From the dispensing side, I'd put my mone on the fact that you could fit .25 cyls all day with a +/- 10 degree tolerance and have better success than the doctor who attempts to get the 2 degree tolerance.

    Of course you can't argue with a "doctor's" Degree :hammer:, so refer this one to your competition and find some realistic accounts.

  3. #3
    Rising Star Monkeysee's Avatar
    Join Date
    Oct 2004
    Location
    Canada
    Occupation
    Ophthalmic Technician
    Posts
    103

    Confused

    Hey, thanks for your thoughts Homer. Unfortunately this doc owns the lab.. I do work solely for him, (I should've been more specific), I'm just not "on site", but have the finishing lab 2 blocks away from his office. Also when they "reject" a job that is off axis, it means it sits on his desk while he thinks about it.
    Last edited by Monkeysee; 11-28-2004 at 02:18 PM.
    Chimperial Optical-what a great place to work!

  4. #4
    Master OptiBoarder LENNY's Avatar
    Join Date
    May 2000
    Location
    BROOKLYNSK, NY USA
    Occupation
    Dispensing Optician
    Posts
    4,351
    Next time you talk to him ask him how close he can figure out an axis on his patient!?
    Or maybe he uses an autorefractor to give him 17 axis on -0.25 cyl!

    Good luck!

  5. #5
    Master OptiBoarder LENNY's Avatar
    Join Date
    May 2000
    Location
    BROOKLYNSK, NY USA
    Occupation
    Dispensing Optician
    Posts
    4,351
    Does Chimperial optical has anything to do with Chimps ownership?

  6. #6
    Master OptiBoarder OptiBoard Gold Supporter Judy Canty's Avatar
    Join Date
    May 2000
    Location
    Virginia Beach, VA
    Occupation
    Dispensing Optician
    Posts
    7,482
    This is worthy of an email to our resident genius Mr. Meister. If I am not mistaken, he's been a significant participant in the formulation of the ANSI requirements. Perhaps he can give your Doc some insight into the process.

  7. #7
    since 1964 Homer's Avatar
    Join Date
    Jan 2001
    Location
    Estes Park, Colorado, usa
    Occupation
    Dispensing Optician
    Posts
    754

    Monkeysee

    Ask you boss - forget the doctor issue - "as a businessman does he want his lab to be profitable or not?" If not then you optical-grunts will have to decide if the paycheck is worth the daily abuse.

    If he does want it profitable, he will have to either be reasonable (his track record seems to say he is not) or close the doors and just send is work out to a commercial optical.

    The one who plays the organ gets the coins, the monkeys get only peanuts!
    sounds like he is giving you spoiled peanuts at that.

  8. #8
    Underemployed Genius Jacqui's Avatar
    Join Date
    Oct 2003
    Location
    Frostbite Falls, Mn.
    Occupation
    Optical Wholesale Lab (other positions)
    Posts
    7,417
    In a way I agree with your doctor, ANSI standards aren't really that good. However with a 0.25 cyl. it's hard to get any of them exact. I was trained to use the AOA standards which are much tighter than the ANSI and still use them in the lab, these still allow 3 degrees tolerance which at times is hard to hold.

  9. #9
    What's up? drk's Avatar
    Join Date
    Mar 2004
    Location
    Ohio
    Occupation
    Optometrist
    Posts
    9,388
    This guy sounds like a control-freak. Don't worry about it or take it personally, that's why you have a job opportunity, since no w/s lab would put up with the unrealistic expectations. Keep remaking it as tight as you can get it; if it costs him, fine. If he fires you for not being able to do the impossible, fine. If you can play the game and shrug off the pressure, you might make it where others have failed. Best wishes.

  10. #10
    Pomposity! Spexvet's Avatar
    Join Date
    Jul 2004
    Location
    On my soapbox
    Occupation
    Dispensing Optician
    Posts
    3,760
    I was under the impression that ANSI standards were made by ophthalmologists. Am I wrong? Standard for .25 cyl is 7 degrees. The boss needs to remember that the ultimate judge to accept the glasses is the patient. That means if it's off 2 degrees, and it bothers the patient, it needs to be corrected. If it's off 7 degrees, and the patient is satisfied, it's a done deal.
    ...Just ask me...

  11. #11
    One eye sees, the other feels OptiBoard Silver Supporter
    Join Date
    Jul 2002
    Location
    Wauwatosa Wi
    Occupation
    Dispensing Optician
    Posts
    5,458
    The '95 Z80 axis tolerance for a .25DC is +/- 7 degrees. Over 1.50DC it's +/- two degrees. From my experience folks with cylinder powers over 3.00DC can easily see/feel the difference if the axis is off by two degrees. If I was concerned about prescribing/dispensing/fabricating quality ophthalmic lenses the last place I would start is with the axis accuracy of .25DC lenses. So I would question the doctors priorities, and so should you. Might be easier over a couple of glasses and a bottle of Crown Royal or whatever mental lubricant you find appropriate.

    Good luck,

    Robert

  12. #12
    Master OptiBoarder Texas Ranger's Avatar
    Join Date
    May 2000
    Location
    Republic of Texas
    Posts
    1,433
    I have filled rx's that were pl. -.50 x 67 1/2, this doctor can refract to 1/2 degrees, i'm amazed! the same doc will refract the pt two years later, write an rx for +.50 -.075 x 70 1/2, and tell the pt that there's not enough change to have the rx filled...so the pt, has carried it around for 4 months, thinking that they really would like to see better, and they are so very surprised when they get the new lenses that they CAN see much better; then it's "why'd they doctor tell me it was not enough change"? this is my pet peeve, but I see this on a daily basis, the doc thinks that you can make something to a 1/2 degree (zero tolerance), but that the same pt can't tell the difference of +.50 -.25 ?

  13. #13
    Manuf. Lens Surface Treatments
    Join Date
    Aug 2002
    Location
    in Naples FL for the Winter months
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    23,240

    On The Dot ............................

    Quote Originally Posted by Monkeysee

    I do finishing work for an OD who insists all axis, regardless of power, be within 2 degrees-he says the ANSI standards were just "made up" by Labs to save money on redo's...........................Any feedback would be great.
    We all have learned what the tolerances should be. This does not mean that we have to follow them.

    A maximum tolerance is the ultimate mistake that is allowable by different standards around the world.

    That does not mean it has to be accepted by everybody. Some people want absolute perfection. Each professional who refracts has his own tolerance level for acceptance of finished glasses.


    ANSI standards are an acceptable guide line for the optical profession taking off powers and off axis into consideration compared to the power level of the prescription.


    If you don't like the level of acceptance of your boss, go work for somedody that does. On the other hand you will be trained to supply perfect jobs and that will get you an advantage in your profession.


    Actually if I would have to buy glasses I would prefer to get them from somebody that insist's on perfect jobs than from somebody that is happy with a job that is kept within tolerance levels.

    (suggestion: check callibration of your and the doc's lensometer for power and axis)

  14. #14
    That Boy Ain't Right Blake's Avatar
    Join Date
    May 2000
    Location
    Mobile, AL, USA
    Occupation
    Optical Laboratory Technician
    Posts
    543
    While it's admirable to strive for absolute perfection every time, the truth is that sometimes you have to draw the line somewhere else. It is my understanding that the tolerances are based on two things: what you equipment is capable of producing and what the patient can tolerate.
    If I am edging a flat top bifocal with a seg height of 22mm, and it comes out at 21 1/2, should I remake the lens, or should the glasses be adjusted to compensate? On the other hand, if a lens is 0.25D strong, I'll just re-fine it on a new tool. But there is no sense in re-doing something over and over striving for 100% perfection when 99.9% will do.

  15. #15
    Rising Star Monkeysee's Avatar
    Join Date
    Oct 2004
    Location
    Canada
    Occupation
    Ophthalmic Technician
    Posts
    103
    Thank you for all the replies so far, so nice to have all this feedback. The lensometer calibration is something to look into, but would we not have discrepancies between the two on other Rx's? not just the 0.25 cyls? It just bothers me that different people get different readings from different/same machines, so how do you know who's right? With optical association standards ranging from 3 to 7 degrees,(and I also heard 9 from another source), and in my case "2", I have to assume my employers standard is based on "psychological" standards rather than "scientific" ones, (seem reasonable?), and grin and bear it!!!(and enjoy those peanuts). Would like to know how the ANSI standards are determined though?
    Chimperial Optical-what a great place to work!

  16. #16
    Forever Liz's Dad Steve Machol's Avatar
    Join Date
    Apr 2000
    Location
    Back in AZ
    Occupation
    Other Eyecare-Related Field
    Posts
    10,252
    On a related note, wouldn't the visual affect of an off-axis 0.25 cyl depend on the overall Rx?

    For instance, wouldn't 10 degrees off axis be more troublesome in this Rx:

    Plano sph -0.25 cyl

    Than this one:

    -12.00 sph -0.25 cyl

    I never understood why the ANSI standards don't take this in consideration (other than the obvious fact this this complicates the writing and understanding of the standards.)


    OptiBoard Administrator
    ----
    OptiBoard has been proudly serving the Eyecare Community since 1995.

  17. #17
    Master OptiBoarder Texas Ranger's Avatar
    Join Date
    May 2000
    Location
    Republic of Texas
    Posts
    1,433
    A basic assumption is that you can actually make an eyeglass lens that perfectly emulates the trial/phoropter lenses, which is impossible. the spheres and cyls are two seperate lenses in the exam process, and the cyl may even be in plus cyl form. and the degree marks are not all there, so there is even some "judgement" on the part of the refractionist. then it's likely that the rx glasses lenses are going to have different size/thickness and curve factors, as well as vertex distance factors, and then there can be variables for monocular pds/seg hts, etc. so, yes Blake you order a 22 seg ht, and it comes out 21.5, so was there some scientific reason that you didn't order 21.5 to begin with ? does it matter to the wearer? NOT. some rxs can be 0.12 off, or even 0.25 on higher powers, but the direction is more important than the amount. the average pt. has a hard time determining the pricise axis of 0.25 cyl, regardless of the sphere power. We'd all like to dispense "perfect" eyewear, but, realistically, I'm not sure I've seen a pair, ever...some that are incredibly close, but you can always find something that could have been better, can't you?

  18. #18
    Master OptiBoarder LENNY's Avatar
    Join Date
    May 2000
    Location
    BROOKLYNSK, NY USA
    Occupation
    Dispensing Optician
    Posts
    4,351
    Steve said : or instance, wouldn't 10 degrees off axis be more troublesome in this Rx:

    Plano sph -0.25 cyl

    Than this one:

    -12.00 sph -0.25 cyl


    I will stand on my point . Doctor has to be not very smart to give an RX of -12.00-0.25 with any axis!!!!
    Just my experience!

  19. #19
    Banned
    Join Date
    Jun 2000
    Location
    Only City in the World built over a Volcano
    Occupation
    Dispensing Optician
    Posts
    12,996
    If he owns the lab, let him know how much the re-makes cost him.The re-makes will slow down a lot.

    :cheers:

  20. #20
    Manuf. Lens Surface Treatments
    Join Date
    Aug 2002
    Location
    in Naples FL for the Winter months
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    23,240

    Calibration of Lensometer .......................

    Quote Originally Posted by Monkeysee

    ................ The lensometer calibration is something to look into, .................... not just the 0.25 cyls?

    If you take a + or - plao cylinder lens between 2 and 4 D grid a straight line for a base and use this for calibration, get it dead on on your and his lensometer, he will never see a 2 degrees off on his lensometer with a +- 0.25 cyl.
    That should clear the case.

  21. #21
    Bad address email on file
    Join Date
    May 2000
    Location
    Richmond, Va
    Occupation
    Lens Manufacturer
    Posts
    160
    When I started in the business many moons ago one of the first things that I was taught is that no two people will always read the axis on a 0.25 cylinder the same. The difference in reading between two people on the same machine can easily be 5 degrees different.

    I know it is hard to believe but I have ran my own comparisons with people using the same machine and the same RX and had each individual write down the results. I found that the axis could vary up to 13 degrees on some jobs between two different people.

    Jerry

  22. #22
    Rising Star Monkeysee's Avatar
    Join Date
    Oct 2004
    Location
    Canada
    Occupation
    Ophthalmic Technician
    Posts
    103
    Chris: pardon my ignorance, I'm not sure what you mean by marking a grid on the base line and power of lens I should be using?


    I'm thinking it's this type of test/demo: Take a plano-2.00, a plano-0.25,(and maybe a plano-1.00 as well for arguments sake), uncut blanks and dot each one up on my Reichert lensometer at the same axis, (180?). Then have the OD and his assistant each dot up those same lenses, at the same axis, on their lensometer (marco LM770), we will very likely get 3 different readings on the 0.25 cyl. but not the others. As they've never rejected a lens with a 0.75 cyl or higher for being off axis, (once in a blue moon they find a 0.50 cyl off), at least I would hope to show that it is not sloppiness on my part causing these discrepancies and may put a stop to those "wonderful" memos I dread getting:angry:
    Last edited by Monkeysee; 11-28-2004 at 02:12 PM.
    Chimperial Optical-what a great place to work!

  23. #23
    Rising Star Monkeysee's Avatar
    Join Date
    Oct 2004
    Location
    Canada
    Occupation
    Ophthalmic Technician
    Posts
    103
    Quote Originally Posted by LENNY
    Does Chimperial optical has anything to do with Chimps ownership?
    "Chimperial Optical ", (Imperial Optical-now long gone-too much monkey business), is actually where I got my first job in this profession....we didn't refer to ourselves as "lab rats", but as "chimployees"...it was kind of a fun place to work.:)
    Chimperial Optical-what a great place to work!

  24. #24
    Master OptiBoarder rep's Avatar
    Join Date
    Oct 2000
    Location
    Red State in The South
    Occupation
    Other Eyecare-Related Field
    Posts
    770

    Ansi

    ANSI stands for the American National Standards Institute. It is 85 years old. The standards for optical were developed and are maintained by a board consisting of Ophthalmologist, Optometrist Opticians, and various manufacturing association trade representatives. Richard Sanders served on this board for more than 10 years. I do not know who represents opticianary today thru the NAO.

    This is a pretty important group, as the europeans are always trying to change the standards which would effect every measuring instrument currently in use in the industry. Imagine having a standard other than .12/.25 diopers and having to adjust or recalculate every measurement.

    Even thought the standards are voluntary they have and will stand up in court as evidence that a prescription is manufactured as prescribed.

    In my opinion anybody that has ever refracted knows that you cannot consistently measure .25 cyls axis's accurately. First of all patients are not consistently in their determination as to which is better 1 or 2 and any OD or MD than says they can consistently scope .25 cyls is blowing smoke. Most patients eyes are not the same every day because of changes in the body. Some days the axis is 5 degrees one direction and other days it is 5 degrees te other direction.

    The more important issue is the placement of the optical center in weak cyl's especially with low spherical powers. They tend to wander all over the place and this can cause some patient complaints especially if they have an occupation that requires extremely critical vision.

    It's a nice warm fuzzy feeling to strive to be more accurate but unless the laboratory equipment changes to some of the new european equipment capabilities (tenth of a diopter and higher). Consistient accuracy beyond .25 diopters is probably unattainable. If that happens and ANSI changes the standard, every lensometer in America will instantly become useless because of the potential liablilty of making glasses at a standard lower than ANSI. Be careful what you wish for. The bigger question is would the public actually be able to notice any difference. I think that is very unlikely.

    Steve since the ANZI standard ( best of my recollcetion ) is .50 diopers on lenses over 10.00d why would you be concerned about a .25 cyl off 5 degrees in any meridian for a -12.00 sphere? The maximum in any meridian is going to be -12.25 which is less than the ANZI standard for this power lens.


    Rep

  25. #25
    Rep,

    Ansi for Sphere above 6diopters is 2% of total power. So tolerance for 10 diopters is .2 diopters or round to a quarter.

    However to determine If one should pass -.25cyl outside of ansi, I would ask is it with or against the rule?

    Also ansi for -.25 cyl is 7 degrees not 5.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Axis Problem
    By CKPolar in forum Ophthalmic Optics
    Replies: 14
    Last Post: 06-17-2005, 11:42 PM
  2. Progressives and Axis
    By edKENdance in forum Ophthalmic Optics
    Replies: 28
    Last Post: 10-09-2003, 05:35 PM
  3. Chuckles
    By chm2023 in forum Just Conversation
    Replies: 2
    Last Post: 04-02-2003, 01:18 AM
  4. Off Axis???
    By Rex in forum General Optics and Eyecare Discussion Forum
    Replies: 5
    Last Post: 08-11-2000, 04:08 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •