Glasses Prescription + vs. - cyl

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Hi, 

I went to see a new optometrist recently and he gave me a new prescription in + cyl rather than -cyl, which is what my previous optometrist used to write. I want to be sure that I am getting the correct prescription  because it seems drastically different from my old one and my vision really hasn't gotten much worse - could someone please tell me what this would be as written in -cyl? Thanks much. 

OD

SPH -4.25

CYL  +.50

AXIS 111

OS -5.25

CYL +.75

AXIS 075

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  • Posted

    OD = right :  -3.75 sph, -0.50 axis 21

    OS = left  :   -4.50 sph, -0.75 axis 165 degrees

    any optometrist is competent to switch between + and - cylinders.

    It makes no difference to the manufacturer or glasses wearer.

    Hope this seems closer to what you were expecting :-)

     

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    • Posted

      Thank you. This does seem much closer to my prescription from last year:

      OD -4.00 Cyl -0.50 Axis 025

      OS -4.00 Cyl -1.00 Axis 170

      Update: for the last couple of weeks since I posted this, I have been trying to adjust to my new glasses with the prescription in my first message and I seem to be having a hard time. My head gets tired and I develop what I would describe small headaches, and I have gotten dizzy one time when I wore them outside in bright sun light.

      I cannot think of anything other than my new glasses that could have caused this. So I am trying to decide whether to go back to the doctor and have him adjust my prescription.

      The only other difference between these glasses and my previous ones other than the seemingly small change in prescription is that these have the blue light blocking Crizal Prevencia lenses (anti blue-blocking light from computer screenns, smart phones, etc). So if these glasses are giving me headaches, I don't know whether it's the small change in prescription or the blue light blocking properties of the lenses (I hear that some people have trouble adjusting to them).

      To be honest, I have been avoiding wearing these new glasses although I have been trying them more and more lately as I really want to decide very soon whether a trip back to the doctor is in order. Is it possible that going back to my old glasses is also the problem? Since the prescription changed so little, I was really wanting to have this as a second pair of glasses, but it's really turning out to be quite stressful to wear them. 

      Any thoughts on this and recommendations on what to do?

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    • Posted

      Are your spectacles varifocal as then positioning is critical up and down on your face.

      Do you find a diffference if the glasses are spectacles are moved towards or away from your eyes (this makes the difference weaker or stronger respectively)  - adjusting this permanently means tweaking the nose pieces or arms.

      Diffenrent lenses come in different "form factors" which can make a difference.

      Try these things, try wearing your glasses little and often.  If you get a headache or eye strain take a break.  If symptoms persist go see your optometrist.  It may be a problem of lens centration causing a prism effect...

      I don't see how a blue filter (making the lenses appear orange) should make much difference.

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    • Posted

      Hi Robert,

      I hope you are still on this forum as I have a follow-up to the above, and would really appreciate your input. Sorry this is a bit long-winded, but I wanted to spell everything out, so that you can provide focused comments. (I know that you are a doctor, but I spell out the terms below for other readers who may not be familiar with the terminology). Thanks in advance for your feedback! 

      Since my last post, I have updated my prescription (it was screwed up as I suspected). I currently wear my new prescription glasses that have Essilor’s Crizal Prevencia (blue light blocking) lenses. The glasses are right on the prescription, but have noticeable chromatic aberration. When I look at really light objects, there is a yellow border on one edge, and an indigo one on the opposite edge. Sometimes, I also see an indigo border going all the way around around black computer keys. I also have a problem on really bright days when I am around areas that have a lot of snow on the ground and it is really bright out. My optician says that this is «normal» and «happens» with blue blocking lenses. She also says that this is nothing to worry about. My question is twofold: 

      1) Is there any evidence that this type and amount of chromatic aberration bad for one's vision? It is rather annoying, or at least unusual as I've never had it with any of my previous lenses (same prescription strength), but is there any evidence that it's actually harmful longterm? 

      2) I have been trying to review the literature on blue blocking light lenses. The kind that Essilor makes reflects a specific range of blue light. The lenses themselves are clear and not yellow as some of the earlier lenses on the market, but you do see a purple light reflection when you hold up the lenses to light. 

      The only scientific litearture I have been able to find on the harm of blue light is from Essilor itself. The main piece of evidence as far as I can tell, is a study done by Essilor scientists in conjunction with the Paris Vision Institute who cultured pig retinal pigment epithelial cells and exposed them to the specific range of blue light that is emitted from modern LED-carrying technologies (415-455nm). They found that when they exposed cells to wavelengths between 415-455nm there was a higher rate of apoptosis (programmed cell death) compared to untreated control cells. These cells also accumulated A2E, a fluorophore (fluorescent pigment) that accumulates along with lipofuscin, a complex of proteins and lipids that is basically the cells dumping ground for molecules that have outserved their usefulness, but have not been recycled or cleared by the cell. 

      Now, as far as I can tell this is the ONLY piece of evidence for claiming that blue light in the range of 415-455nm is harmful to the eye and may lead to macular degeneration over time (besides some other older studies that have also used cell experiments that used similar types of cells). This to me seems far from conclusive, and I am just surprised that an ENTIRE industry basically sprung up around this single piece/type of evidence!

      Are you aware of any other studies which show that blue light in the 415-455nm range is harmful in the long-term? Perhaps in animal models? What are your thoughts on the matter?

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