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what is my glasses prescription if my contacts are?

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How can I get a contact prescription from a glasses prescription?
Left Eye = -5.25 Sph , Cyl -2.00, Axis 17. Right Eye = -5.50 Sph, -2.25 Cyl, Axis 177? Thanks!
Could someone provide best fit based on my updated glasses prescription. I use soft Acuvue Oasis for Astigmatism at the moment. I notice all the formulas online, but would prefer to have someone more knowledgeable confirm. Planning on using Acuvue Oasis for Astigmatism Soft 1 day lenses now. Much appreciated.

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asked Feb 18, 2017 in Health by Pheobe
edited Feb 18, 2017

4 Answers

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With the limited background that you have offered in this question, I will do my best to offer some guidance.

First, the spectacle lens prescriptions are not made exactly in the same power as the contact lenses. Manufacturers make lenses in certain powers and don't make them custom.
To derive a contact lens prescription from just the spectacle prescription in your power range will most likely create ill will between you and who ever attempts to do this because it will likely  take 2-10 iterations before you'll be happy.
People who work with people who are unhappy with them for their work would like to get paid for being unhappy with them
If you are desperate to replace your contact lens prescriptions, you can always ask any retailer to sell you lenses on your old prescription which might be in violation of state law, but I have seen retailers do this.
In my opinion, you course of action is not wise.

You are asking me about a sign or symptom of a potential medical problem and I recommend that you see an eye care professional for your particular concerns. What I write here is not medical, legal or financial advice. This is not a solicitation.
answered Feb 18, 2017 by Richard Hom
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You can’t. Contact lenses not only involve a prescription, but also base curvature and diameter. How the lens sits in your eye, the lens material, and your tear film can all affect the fit. My prescription was similar to yours but with far less myopia and it took 4 trial pairs to get me to see properly. For one thing the lens in my right eye tended to rotate a lot and we ended up with an axis about 15 degrees off my eyeglass prescription!

Do yourself a favour and go to a good optometrist experiences in fitting contacts, pay the fee, and get lenses that fit you well.

Also- do not assume that any one brand or model will work for you, they may not even with the same nominal prescription.
answered Feb 18, 2017 by Patrick James Morley
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Eyeglass prescription and Contact lenses prescription are not the not the same. They differ significantly because of their positioning. Glass lens is placed approximately 12 millimeters away from your eyes in order to focus the power of the lens properly to the eyes, whereas contact lens is placed or rested directly on the surface of your eyes.

 Most of the people assume that the prescription of contact lenses and eyeglasses are similar and create problems associated with their eyesight.

An eyeglass prescription is particularly for the purchase of your desired glasses only. It does not coincide with the information on contact lens prescription. Contact lenses can be obtained only through eye consultation and fitting.

As like an eyeglass prescription, a contact lens prescription includes the power of the lens, which is required mainly to correct your refractive errors such as hyperopia (farsightedness), myopia (nearsightedness) and astigmatism.

Based on the degree of your refractive error and the suitable type of contacts that is prescribed, the power is measured in diopters and is specified on your contact lens prescription. It may be significantly different from your glasses prescription because of the best vision possibility.
answered Feb 18, 2017 by Bipasha Mukherjee
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How do I figure out my glasses prescription from my contact lense box?
My lenses box reads D -4.50
BC 8.7
DIA 14.0

The fill in glasses thing (ordering them online) has slots for the following

Also my eyes have gotten slightly worse from the point when I first got my contacts so if you could factor that in when giving me the conversion. Thanks.

Note: The first pair are free which is why I ordering them online I would call my eye doctor but she would probably resist giving me it so she can get more money.
answered Feb 18, 2017 by JayDee
There are a couple issues with doing this, if you have a small amount of astigmatism, sometimes they just add 1/2 the cylinder to the sphere so you can get the cheaper contacts, also when the prescription gets stronger than -4.00 they start backing off a bit on the strength of the contacts to compensate for the fact that contacts sit right on your eyes vs glasses that are about 1/2 inch away, etc. So trying to get an accurate glasses prescription from your contacts prescription is tough.
However, when they measured your eyes for the contacts, they generally determine your eyeglasses prescription first and work from that, so you should be able to get a copy of it (usually for free) from wherever you got the contacts.
It sounds like your lenses are regular spherical lenses. Parameters "CYLinder" and "Axis" are only applicable for astigmatism glasses - but it is not clear from your contact lens prescription whether you need the astigmatism lenses, and what the Axis and the Cylinder should be. Sometimes it happens that people receive toric (astigmatism) prescription for eyeglasses, and spherical for contacts, but not always. Even if the type of prescriptions is the same, the parameters would usually be different, because the contacts, sitting right on the eye, correct differently from eyeglasses. Thus, it is not prudent to try to derive the eyeglass prescription from contact lens script, and vice versa - you can end up with the wrong glasses and be highly uncomfortable, not to mention that then you will need to redo your glasses and lose the "free first pair" discount. You should absolutely get the script from your doctor, rather than guess. PD (Pupillary Distance) is the distance between the pupils of your eyes - it has no relevance for contact lenses, and something that any optician can measure for you if you just stop by a local optical store.
Your contacts prescription MIGHT be the same as your eyeglasses prescription but, quite often, it is NOT. Also you don't know your base curve and diameter, etc. The probability of you guessing the correct contacts that would work for you from all the combinations available would be pretty slight. In the US, you have to have an exam/fitting and prescription before contacts can be dispensed. Even the on-line places have to abide by this law. You really need to get a proper exam & fitting. If you don't have the money, save up for it and go somewhere cheap like Walmarts. Added: I think you will find that somewhere in the ordering process for contacts, they will want contact info (no pun intended) for your eye doctor to confirm the prescription is valid or sometimes they have you fax a signed and dated prescription, etc. Of course, there might be a few sketchy, fly-by-night operations that will sell contacts to people without a prescription. The problem is, if people wear contacts that don't fit right or don't know how to take care of them, etc, it can cause major eye problems.

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