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Doctor insights on: How Can I Tell How Bad My Vision Is From My Contact Lens Prescription

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How can I tell how bad my vision is from my contact lens prescription?

How can I tell how bad my vision is from my contact lens prescription?

Look for the power: The prescription includes power, base curve, diameter. The higher the power, the stronger the prescription in either myopia (-) or hyperopia (+). ...Read more

Dr. Richard Bensinger
1,734 Doctors shared insights

Vision (Definition)

Vision is a feature of a person's brain that allows him to see. He must have normal eyes, optic nerves (that stretch from the eyes to the back of his brain), and visual cortex (the vision center in the brain), in order to see properly. An ophthalmologist is a ...Read more


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Can your contact lens prescription tell you what kind of vision you have (ie. 20/20)?

Can your contact lens prescription tell you what kind of vision you have (ie. 20/20)?

No: Your prescription tells you if you are myopic, hyperopic, and/or if you have astigmatism. It doesn't tell you how far down the chart you can read, but with the correct prescription you should see 20/20 assuming no ocular pathology to limit your vision potential. ...Read more

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My contact lens prescription has changed twice in 9 mos. Because my close up reading vision has improved. Is this unusual for someone who is 59?

My contact lens prescription has changed twice in 9 mos. Because my close up reading vision has improved. Is this unusual for someone who is 59?

No: Your eyes may be changing as a result of nuclear sclerosis, which is hardening of your lens of your eye creating more nearsightedness. Your prescription would be changing as a consequence. Furthermore, the elasticity of the eye does change very gradually over time. Your eye doctor can help you with this and adjust as necessary. Btw, glaucoma treatments sometimes accelerate cataract formation too. ...Read more

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Could you tell me if my contact lens prescription is -4.00/-4.50 what is my glasses prescription?

Could you tell me if my contact lens prescription is -4.00/-4.50 what is my glasses prescription?

Close: Commonly it is slightly higer like -4.50 and -5.00 but this depends in part on the goal and how long since your last examination. Also at your age there is the issue of bifocals due to near vision needs. Useful to check with your ophthalmologist for the best information on this. ...Read more

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How do I know if my contact lens prescription bad enough to actually need contact lenses?

How do I know if my contact lens prescription bad enough to actually need contact lenses?

Comparison: I am not an eye guy, but scientifically thinking, I would get another opinion, test your vision with contacts on and contacts off. Which is better? ...Read more

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Are optometrists able to tell what my contact lens prescription are by just looking at your glasses?

No: Fitting of contact lenses involves more than just the power of your corrective lenses. The corneal curvature, size of your cornea and general health of the anterior surface of your eye are taken into consideration. How your eye tolerates a specific contact lens is determined during the followup phase of your fitting. ...Read more

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How to read my contact lens prescription?

How to read my contact lens prescription?

It is: A set of parameters that determines the type, power and fit of the contact lens. It is not written in an easy to understand manner. Ask your eye doctor's staff for an explanation. ...Read more

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Why does my contact lens prescription change so much?

Why does my contact lens prescription change so much?

Depends: Prescriptions for glasses and contact lenses can change quite quickly, especially in younger individuals, and in those individuals performing lots of near-vision tasks like reading, computer use, or video games. It is also possible for diabetes and blood sugar changes to affect the prescription, and rarely certain medications can cause this too. Be checked by your eye md if your rx is changing. ...Read more

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I don't know how to read my contact lens prescription? .Help?

I don't know how to read my contact lens prescription? .Help?

Why?: The prescription is designed so the supplier of the lenses can get the proper ones for you. They are very specific. Why do you need to know it exactly yourself. If you are ordering on line, all the information should be there as well. The doctor who gave you the prescription can interpret it for you. ...Read more

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What to do if I do not know how to read my contact lens prescription!?

Training: If you cannot read it because the handwriting is bad, then ask for a replacement. If you want to understand what it means ask the ophthalmologist who wrote it. Otherwise your best bet is to attend opticianry school or medical school followed by an eye training program, and then you can understand the prescription. ...Read more

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What to do if I got my contact lens prescription yesterday. Can this be used for any contacts?

Unlikely: Contact lens dispensers are obsessed with all the information being on the prescription so they can sell you the contacts, get the profit, but take absolutely no responsibility. So your prescription is for one type only and you will need to go to your ophthalmologist to get one for any other type of lens. ...Read more

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What would you suggest I do to convert my contact lens prescription into eyeglass prescription?

Your doc is needed: Depending how near are farsighted you are, there are special formulas to determine this. Your eye doctor should be able to give you a prescription for both. ...Read more

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Is it okay to convert my glasses prescription to my contact lens prescription?

Is it okay to convert my glasses prescription to my contact lens prescription?

Not really: The contact lens rx is determined from a refraction for glasses - sometimes trial fitting is necessary since the actual numbers are different due to an optical property called vertex distance. ...Read more

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My contact lens prescription is significantly different from my glasses prescription. Is this normal?

A small difference: Is normal. A significant difference would be unusual but it could just be the way it is written in a different format. ...Read more

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My contact lens prescription is different from my glasses prescription. Is it supposed to be like that?

My contact lens prescription is different from my glasses prescription. Is it supposed to be like that?

Yes: The optical principle is lens effectivity. As any lens is moved away from your eye it becomes inherently more powerful (positive) the inverse is also true, as a lens is moved to eye, becomes weaker (negative). So contacts and glasses are adjusted accordingly only if it will affect the final clinical outcome. ...Read more

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Is it safe to use my contact lens prescription values for eyeglasses?

Not correct: Eyeglasses and contacts lens prescriptions are not the same. There is a power difference since the glasses are farther from the cornea surface compared to contact lens. Thus you need a different prescription, plus contact lens requires a base curve and diameter in addition to the power. ...Read more

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Why does my contact lens prescription change so much every time I go to the doctor?

Not everyone stable: In some people, the glasses and contact lens powers seem to change annually. These are usually younger patients and occasionally older patients with cataract formation. Usually, most people stabilize by their mid 20's. Drastic changes in refraction may mean problems such as keratoconous or cataract. Best to have a dilated exam. ...Read more

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Can you advise for contact lens prescription?

Not from afar: Contact lenses require measurement of the vision parameters, and assessment of the curvature of the eye. This requires hands on evaluation preferably by an ophthalmologist. That would be the best starting place. ...Read more

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Wanted to know where can I get a free contact lens prescription without purchase?

Many places: Most eye doctors will give you a contact lens prescription to be used anywhere you would like and in fact have to do this by law in most cases. You will have to pay for the examination and measurements. It is after all a service that you would not expect to be given for free. ...Read more

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Is there a way to get contact lens prescription, even though I don't need contacts?

Yes but why: A contact lens with no prescription is called plano which means zero correction. Many colored contact lenses are in this prescription. There is no reason to wear a non-corrective contact lens unless you want a color changer. ...Read more

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I want to know what is the difference between a +5.50 contact lens prescription and a -5.50 prescription?

Significant: The minus power corrects myopia and the plus power corrects hyperopia. They are quite different and cannot be interchanged. If you need one of these, you are very unlikely to need the other and it would given you very uncomfortable vision. ...Read more

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How to get contact lens prescription without a contact lens fitting?

Not recommended: I would not recommend this. Your eyes are so precious, why would you want to take a chance on them? Make sure you get the right kind for your eyes. Make sure there is nothing wrong with them too. Save up a little more and get them fitted the right way. Your eyes are worth it! ...Read more

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What would you suggest I do to convert my glasses prescription to contact lens prescription?

Slightly tricky: Mostly straightforward if there is no astigmatism but a little involved if there is astigmatism. I assume you are ordering lenses online and will need that conversion. There is also some experience functions depending upon the type of lens. Check with your ophthalmologist to get this done for you. Optometrists are unlikely to do it as they prefer to sell you lenses. ...Read more

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Can an eye doctor know your contact lens prescription just by looking at your glasses?

Can an eye doctor know your contact lens prescription just by looking at your glasses?

To some degree: If your glasses prescription is known, your contact prescription should be as well. If the eye doctor just looks at the glasses with his/her naked eye, he/she may get a rough idea of your prescription. If they look at the glasses with a lens meter, he/she will know the glasses' exact prescription, and have a good idea of the contact prescription based on that. ...Read more

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Will the eye doctor give me a contact lens prescription if it's my first time wearing a corrective lense?

Yes: Yes if your correction is amenable to contacts. Your doctor will also check the health of your eye to see if your eye would tolerate wearing a contact lens. ...Read more

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Please tell me what information do you need when ordering prescription contact lenses over the phone?

A prescription: Base curve, size, sphere, cylinder, axis and manufacturer and name of contcat lens, also which eye. ...Read more

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How often do contact lens prescriptions change?

How often do contact lens prescriptions change?

Contact lenses: It is impossible to predict whether the prescription will change or remain the same. Factors that may influence a change in prescription include age, growth of the eye, how much reading/studying one does, medical conditions such as diabetes, growth/progression of cataracts, etc. ...Read more

Dr. Tim Conrad
360 Doctors shared insights

Contact Lens Use (Definition)

A contact lens is a thin plastic or glass lens that is fitted over the colored part of the eye. It may be used for corrective, cosmetic, or therapeutic purposes. ...Read more