Re: New glasses causing trapezoidal distortions

<dadolphson@xxxxxxxxx> wrote in message
news:0b72346b-11b9-46ab-baa4-25c02ad97d47@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
The sphere is remarkably close to the new prescription (-2.50).
Should I just ask them to make me lenses with no Cylinder as such:
OD = Sphere -2.50
OS = Sphere -2.50

Or is Otis correct in how he calculates the "spherical
equivalent" ("Just take 1/2 the "Cyl" value and add it to the stated
Sphere value") which would instead result in:
OD = Sphere -2.75
OS = Sphere -2.75

I don't understand why you want to avoid a cylinder correction for
astigmatism. If it is done correctly, it should not cause any distortion.
You need to focus on the lens design and the lens material and have the lens
made to your original Rx unless the OD thinks it needs to be revised.

Most OD offices and optical shops send out the Rx to a separate lab to make
the lens to your Rx. Some of them will cut the lens to fit the frame when it
comes back from the lab (all lenses are round until the are cut to fit the
frame), and others will have the lab do the whole thing (they send the frame
to the lab). Some stores deal with multiple labs to get various products,
but many like to stick with certain brands (and the associated labs) even
though they could deal with multiple labs if they wanted to. Some labs deal
with multiple lens manufacturers, and some are owned by lens manufacturer
and only make their own brands (I believe Hoya is like this).

The exception to that are the large chains which advertise 1 hour glasses
and have an in store lab. I would avoid them like the plague since the
quality of the lens designs are very mediocre and the choices are limited to
their house brands (unless they send it out to a lab).

Even Walmart sends out their lenses to a lab (although it is a lab owned by
Walmart).


.

Relevant Pages

  • Re: Kimwipes (5*8 wipes) v.s. Lens Paper?
    ... school, whether it be the university biology lab, the colleges lab ... sensitive object (lens) ... Cut a finger off a rubber glove. ... Lenses require careful construction, of course, and don't mess up any ...
    (sci.techniques.microscopy)
  • Re: Kimwipes (5*8 wipes) v.s. Lens Paper?
    ... school, whether it be the university biology lab, the colleges lab ... I personnaly find that lens paper is too smooth and simply is not ... On the other hand, the Kimwipes of the ... Wiping a lens surface dry just scratches the heck out of it, ...
    (sci.techniques.microscopy)
  • Re: Kimwipes (5*8 wipes) v.s. Lens Paper?
    ... school, whether it be the university biology lab, the colleges lab ... I personnaly find that lens paper is too smooth and simply is not ... Cut a finger off a rubber glove. ... residue could then be used with more pressurization simply by queezing ...
    (sci.techniques.microscopy)
  • Re: Gut check on lens pricing...
    ... in fact they are the third largest optical lab chain ... they do have a variety of lenses but mostly based upon ...
    (sci.med.vision)
  • Re: for R. Martellaro, or anyone; question about exec bifocials
    ... suggestion is to find a lab that has more experience with this type of lens. ... This is in the seg only, as I'm getting a prism diopter of jump at the seg line, which I think has got to have been done at blank casting time because it must be coming from the front surface. ... They don't have much control over the blank manufacturing process. ...
    (sci.med.vision)