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Doctor insights on: Visual Acuity Test Snellen Chart

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My eyeglasses prescription is -8.00. What's a best guess at my snellen visual acuity?

My eyeglasses prescription is -8.00. What's a best guess at my snellen visual acuity?

With or without: It depends if you are corrected without any other eye issues then you probably can see 20/20. You cannot see snellen chart without correction therefore there is no measure for it. You probably can see near card at 4-6inches without correction. ...Read more

Visual Acuity (Definition)

Visual acuity is the measure of the sharpness of vision. It is the most important measurement of eye function. In the us, the antiquated snellen visual acuity measurement is most often used. This is the "20/20" thing you have ...Read more


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How can you measure visual acuity w/ the snellen eye chart?

How can you measure visual acuity w/ the snellen eye chart?

Read smallest line: The snellen chart is a graded series of letters or numbers smaller as you go down. The uncorrected vision is the smallest line easily read with each eye. Your ophthalmologist will present you with lenses to improve the level of the smallest line to hopefully get you to 20/20 - the standard of normal. It is a subjective test requiring your active input. ...Read more

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Can you tell me about what it means by visual acuity not exceeding 6/60 or 20/200 (snellen) in the better eye with correcting lenses?

Can you tell me about what it means by visual acuity not exceeding 6/60 or 20/200 (snellen) in the better eye with correcting lenses?

Lowered vision: The 20/200 line (6/60 in metric units) is usually the letters below the big "e" on the standard vision charts. This is also the level for legal blindness in most states. It is quite a lowering of vision and means that with the best eyeglass correction, only that level can be obtained. ...Read more

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What is an example of a bad score on a visual acuity test? When are you bad enough to need glasses to drive?

What is an example of a bad score on a visual acuity test? When are you bad enough to need glasses to drive?

20/40 or Worse: A distance vision test of 20/40 or worse will disqualify you on a dmv physical here in california. They differ state to state, but I believe they are the same. So 20/40, 20/50, 20/60, etc would be examples of worsening vision. 20/20 is perfect. It is what you see from 20 feet / what a normal person sees from. ...Read more

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What is a visual acuity test?

Visual acuity: Acuity tests are standardized charts of various sized objects, usually letters or numbers, which delineate the limits of vision. This can be with or without eyeglass correction. This number can then be used to compare your best vision to others or to legal standards such as the level needed to get a driver's license. It also is used by researchers testing ways to improve vision. ...Read more

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Is there a rough visual acuity test that I can easily perform?

Is there a rough visual acuity test that I can easily perform?

On line: You can "Google" Snellen acuity chart to get a rough idea of the vision. You can also compare the limits of your vision with someones vision who has known acuity. At your age, I assume that you have a driver's license and most likely have had to pass an acuity test to get that license approved. ...Read more

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Are there errors, distortions, or disadvantages of using a mirror in a visual acuity test?

No: No, the image is the same as if you were looking the entire 20 feet (or 6 meters). The virtual image produced by the mirror is 20 feet away. Now, if the mirror is very dirty or dusty, maybe. ...Read more

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How does the mirror affect the eye chart in a visual acuity test?

How does the mirror affect the eye chart in a visual acuity test?

Lengthens light path: Most offices do not have a 20 foot lane. But standards and available charts are made to reflect a 20 foot lane. The way to handle this is to use mirror (s) to reflect the image the proper distance to approximate a 20 foot lane. The letter images can also be enlarged or diminished as needed but this will change the standardization. A 20 foot light path is the standard. ...Read more

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Is there a rough visual acuity test that anyone can perform without the eye chart?

Is there a rough visual acuity test that anyone can perform without the eye chart?

Yes: Your question specifically address visual acuity which is a measure of the acuteness of vision.

If anyone has concerns about their acuity, please visit your optometrist or ophthalmologist.

Acuity is best assessed one eye at a time. Roughly an eye should be able read newsprint (or smaller) at the normal reading distance.

Now, it's easy to download apps for your phone to test acuity. ...Read more

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Is it possible to get accurate visual field test with macular pucker decline in visual acuity, lights less bright & white computer screen looking gray?

Is it possible to get accurate visual field test with macular pucker decline in visual acuity, lights less bright & white computer screen looking gray?

Usually it is fine: You have defects in the central visual portion of your field of view - an area poorly outlined by most field testing devices. Field tests will define major defects which largely will register from the peripheral areas tested. Have you had a field tested in the past? Is there some condition being sought for with a field.? Your ophthalmologist would not order a field if he doubts the result. ...Read more

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My 9 old son had an eye test, was referred to hospital, low visual acuity, stereo found 480 sec arc, and failed visual fields, low concentration??

My 9 old son had an eye test, was referred to hospital, low visual acuity, stereo found 480 sec arc, and failed visual fields, low concentration??

Exam findings: The given information is concerning given your son is most likely beyond the amblyopic treatment age, low stereopsis and the enigmatic "low vision". Key information would be history? Has he seen an eye doctor before now? What is his best acuity corrected visual acuity (with glasses. misalignment of the eyes ("crossing eyes")? Is there any pathology noted on the dilated slit lamp examination? ...Read more

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11 month old diagnosed with decreased vision from visual acuity test (teller). However, prescription test after dilating the eyes shows no prescription needed. Eye health is normal. Why this conflict?

11 month old diagnosed with decreased vision from visual acuity test (teller). However, prescription test after dilating the eyes shows no prescription needed. Eye health is normal. Why this conflict?

The teller cards: Give a good estimate of visual acuity in children. But, since it is testing the first reaction of a child when the card is presented, things like tiredness or distractions can affect the accuracy. The prescription measured after dilation is more of an objective measurement and can be done accurately. Continue follow up as your eye doctor recommended. Be well. ...Read more

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Normal CT of brain within past six mths. Would a symptomatic brain tumor develop quickly since then? Also, normal eye exam and visual acuity tests

Normal CT of brain within past six mths. Would a symptomatic brain tumor develop quickly since then? Also, normal eye exam and visual acuity tests

Unlikely: Unless it is from somewhere else and it is infiltrating type to the tissues. Imagine a speck of tissue not seen six months ago by ct scan. The usual doubling time of a tumor in volume is 3 months. For it to grow and cause symptoms, it has to have been big enough to be seen 6 months ago. ...Read more

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Can docs explain what does visual acuity indicate?

Vision standard: In the USA the standard is the Snellen fraction of 20/20. The upper number means the letters are 20 feet away. The lower is the distance the normal could be to read the number. If someone is 20/200 at best, the letter is large enough that the 20/20 normal could be 200 feet away and still read it. Visual charts have a graded series of letter size to get the best fit. ...Read more

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Is there a way to convert contact lens power to a simple central visual acuity?

Is there a way to convert contact lens power to a simple central visual acuity?

No: The relationship between lens power and the standard vision fraction like 20/20 is not linear. These two items do not interconvert. ...Read more

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Please help? Is the meaning of visual acuity- the "ability to discriminate between two points"?

Close: A better definition would be the measurement of the minimum distance at which two points can be distinguished as two. We use a very weird and ancient way to write this down called snellen acuity. ...Read more

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Can you determine visual acuity by looking at prescription?

No: There is not a direct relationship between Snellen acuity (like 20/20 or so) and the diopters printed on an eyeglass prescription which is the formula used by the optical shop to make your glasses. ...Read more

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Is it necessary to wear glasses if you have distant visual acuity?

No: If you see well at distance without glasses or contacts, that is fine. Not wearing glasses, even if needed, does not hurt or damage your eyes, if you are over 45, you may need reading glasses if you have good distance vision. Or, you can try monovision with a contact lens, with the non-dominant eye set for reading. Lasik in the non-dominant eye for reading might also be an alternative to explore. ...Read more

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Is there a way to determine my visual acuity from my contact prescription?

No: There is not a direct correlation between the refractive numbers on an eyeglass prescription or the numbers on a contact lens prescription. You need a standardized chart and lane to get the actual acuity level. ...Read more

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Is there a way to determine my visual acuity just from my contact lenses perscription?

Is there a way to determine my visual acuity just from my contact lenses perscription?

No: Your prescription is the power of the lens which gives you the best possible vision. It doesn't say anything about what that level of vision is. Your visual acuity is tested wearing your best correction. ...Read more

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How is visual acuity preserved in bitemporal hemianopia?

Nerve fiber pattern: Bitemporal hemianopia is the classic later stage vision pattern in advancing pituitary tumor. Generally the central fibers, which carry the best acuity are affected later in the condition. A great deal of vision loss would have to be ignored by someone with this condition before the nerve fibers for the central acuity start to drop out. ...Read more

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Will visual acuity always determine eyeglass prescription?

No, not always: Visual acuity is a measure of how well you see. In most cases this reflects on what your prescription might be but it can't estimate it exactly. There are many other factors that determine how well you see: if your retina is healthy and if there are other problems with your cornea or lens. It's possible to have poor visual acuity and yet have no need for glasses. ...Read more

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How can you calculate visual acuity based on eyeglass prescription?

How can you calculate visual acuity based on eyeglass prescription?

Simplistic: The simplistic answer is that a good optometrist/ophthalmologist knows what acuity corresponds with what prescription. I don't think you will find a formula to calculate this. ...Read more

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How can I know my visual acuity?

Compare to normal: You can get a rough idea if you have 20/20 by comparing your sight with someone who has perfect vision (or perfect with correction). Both of you view something at the limits of clarity (a sign far away) and if you both read it well, then you are 20/20. To determine lesser sight, you will need an eyechart and a proper lane. ...Read more

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How to find out my visual acuity?

Testing: You can get a rough idea if you have 20/20 by comparing your sight with someone who has perfect vision (or perfect with correction). Both of you view something at the limits of clarity (a sign far away) and if you both read it well, then you are 20/20. To determine lesser sight, you will need an eye chart and a proper lane. It is best to have an ophthalmologist measure it for you. ...Read more

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What's the highest visual acuity?

20/08: A number of younger people can see 20/15 and a few 20/10. I have not seen one at 20/08 but I have read about them. The highest acuity of all is in raptor birds (hawks, eagles, etc.) who can see down to 20/02 according to some accounts. ...Read more