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It was not long ago that my vision was blurry, especially when driving at night, even with the latest prescription. I thought that soon I would need to stop driving at night, but all this changed at the age of 72 when I tested my own eyes and my new progressive glasses gave me very sharp vision for driving at night. Every time I went outside, I was amazed how sharp my vision was. I can see details, such as individual leaves on trees, at a distance. I had not experienced such sharp vision since I got my first glasses as a child.  Even at 75, I still am astonished at how sharp my vision is with glasses.

My vision is much sharper than what I could ever get from glasses prescribed by an optometrist.

Regardless of your age, you can have better eyesight and better glasses. I want everybody to have the same experience I have had, and that is why I created this web site.  The primary purpose of this web site is to provide a step-by-step interactive guide on how to test eyesight using a lens set kit and frame and a Jackson cross cylinder, and get the same results I have achieved.  The web site does more than that.  It provides information on how to obtain the equipment you need for testing, how to obtain the PD and more.

Here is how I first tested my eyes in a nutshell:  I put the lenses in the frame which matched my latest prescription and adjusted the astigmatism angle  (axis) to match the prescription.  Then I tested to see if I needed to make changes for how farsighted or nearsighted the lenses should be (that is called the sphere).  Then I tested to see if there needed to be any changes in the strength of the astigmatism (that is called the cylinder).  Then I tested to see if the angle of the astigmatism had changed (that is called the axis).  I repeated this process until I achieved the best possible prescription or eyeglass numbers.

Instead of testing at 20 feet, I tested at 300 feet, so I would get the best possible glasses for driving.

Testing using this method made sense to me.  You get the best possible sphere, and then you get the best possible cylinder and axis and as a result you have the best possible prescription or eyeglass numbers.  At least that is true in theory.  I liked the glasses, and it was better than I could get from an optometrist, but from the very beginning, I realized there was a better approach using Jackson cross cylinders, but this was an advanced technique which I assumed all optometrists would use, and it was beyond my abilities at the time.

My eyes changed, and it came time to get new glasses.  By that time, I had learned a better way to test eyes and I tested my eyes using the better approach.  This was the advanced technique which I assumed optometrists used.  I ordered the glasses and the results were absolutely phenomenal.  When my new glasses arrived, I was absolutely amazed.  The distance vision was very sharp, and I could see accurately for driving at night.

Great glasses will not fix mild cataracts, but if you have great glasses, it can make a world of difference for driving at night, even if you have mild cataracts.

Since that time, my eyes changed and I tested my eyesight again, and my vision with glasses is astonishingly sharp.

I was wrong when I assumed that optometrists used this advanced technique for testing eyesight.  They are totally unaware of this approach and the advantages it brings.  You can only get these kinds of results by testing your own eyes using a lens set kit and frame and Jackson cross cylinders.

What are some of the advantages that this web site offers?  Optometrists do not test for astigmatism at reading distance.  They test at 20 feet and sometimes less, but never at reading distance.  They know that accurate astigmatism results can not be obtained at reading distance.  Testing at the longer distance of 300 feet gives even more accurate astigmatism results.  The longer testing distance combined with the advanced technique for testing eyes gives much more accurate astigmatism results.

The eyes can focus in and out for closer and more distant viewing, but there is no focusing ability in the eyes to adjust for astigmatism.  When the astigmatism correction is accurate, the natural ability to focus allows the eyes to focus much better and have sharper vision for all different distances.  Therefore, young adults who retain much of their focusing ability benefit tremendously from obtaining accurate astigmatism correction.  Ideally, young adults should test their eyes at 300 feet using this advanced technique, and then retest at 20 feet changing only how far-sighted or near-sighted (sphere) the correction needs to be.  Accurate astigmatism correction also means that glasses might not need to be changed as frequently, because the eyes can more readily adjust to imperfections in the lenses.

What about older adults and senior citizens?  How can they benefit from accurate astigmatism correction?  If you have single-vision glasses, then you are able to see clearly over a wider range of distances.  For example, you will have better ability to see at reading distances using your computer glasses than you would otherwise have.  The range of distances you can see is expanded with accurate astigmatism results.  Progressives also work better.  You can see well at different distances without moving your head up and down as much.  You will have much sharper vision under all circumstances.

What gives this advanced technique such strong advantages over the conventional approach?  With the conventional approach, whenever the strength of the astigmatism (cylinder) is changed, the near-sightedness/far-sightedness (sphere) is also changed with it.  As a result, sometimes the strength of the astigmatism is changed when actually a change in the near-sightedness/farsightedness is needed.  In theory, sometimes adjusting the axis also can mask the problem and take the testing further off-track.  The resulting prescription can be along a range of sphere and cylinder combinations.  In theory, this imperfection should be small, but in actual practice, it can be quite large.  Also, for some unknown reason, testing at a specific distance may give good results at that specific testing distance and still be wrong.

In sharp contrast with this, the advanced technique using the Jackson cross cylinder gets accurate sphere and cylinder results while, to a large extent, it isolates the sphere from the cylinder resulting in a much more accurate cylinder (strength of astigmatism) measurement.

The above is not just theory.  The theory has been established to be correct a number of times by the accuracy of vision in the glasses that are ordered using the advanced technique for testing eyesight.  If this were not true, testeyesight.org would have been designed and written based on the conventional approach instead of the advanced technique for testing eyesight.  When comparisons are made using glasses derived from the conventional approach and glasses using the advanced technique, and the prescriptions are different, the advanced technique always gives superior results, and that is an understatement!  Contact us if you are interested in conducting a double-blind study.

Can an older adult or senior citizen suffer vision loss from not using the advanced technique for testing eyesight?  Yes they can!  An older  adult or senior citizen may think they have lost all ability to focus their eyes in an out for different distances, but unknown to them, a tiny amount of focusing ability remains.  A form of accommodative dysfunction may develop due to extended inaccurate vision correction.  Over time, the eye could stop attempting to focus properly for different distances — not due to a physical inability, but rather a form of learned or functional suppression of the focusing effort.  The eye learns that no matter how it tries to focus, it makes no difference in how accurately you see, so it just starts focusing randomly.  This condition is best prevented by making certain you have accurate vision correction as you age, and the most accurate correction takes place using the advanced technique for testing eyesight.

When children do not have accurate prescriptions, it can permanently compromise their handwriting and their ability to recognize faces and cause academic problems. It can also cause a long list of eye problems that may be difficult to treat. The details on how this works and why are covered in our Conversation with ChatGPT.

A number of other topics are also covered in our Conversation with ChatGPT, and the conversation helps explain more of the reasoning.

Once the process for testing eyes is learned, testing eyesight can be quite speedy.  Keep reading until you see "CLICK HERE" in very large type.  Then you can click on the link to use the interactive guide for testing eyesight.  It is helpful to know details such as prerequisites before testing and many other areas, so let us look forward to the time when you have become familiar with everything before the link and you are ready to use the interactive guide to testing eyesight.

Is there another way to get these results, without using a lens set kit and frame and Jackson cross cylinders?  Yes there is!  Motivated by altruism, I am telling you about https://eyeque.com/

EyeQue works by some hardware which you fasten to your cell phone and you look through it and adjust it using an app.  It is much cheaper than a lens set kit and frame and Jackson cross cylinder, but it does have some disadvantages.  With a lens set kit and frame, you experience the results immediately.  With EyeQue, you don't see the results immediately.  Years ago, EyeQue offered cheap glasses just so one could experience the corrected vision before ordering the glasses you need.  Maybe they still make that offer.  A second disadvantage is that I made mistakes the first time I used it, and years ago, they had no provision to start over with a clean slate.  It took past results and tried to combine it with the latest tests, but since the past results were garbage, so would be the latest results.  Years ago, I could circumvent this problem by creating an entirely new account and using a new e-mail address.  I do not know if this still can be done, but if you want to try that approach, the quickest way to create new, free e-mail addresses is with https://account.proton.me/login?product=generic&language=en

Another problem with EyeQue is that the cheaper models of EyeQue sometimes do not click firmly in place when they are adjusted for different portions of the test, which can result in incorrect results.  I do not think the later models have this problem.

When I first tested EyeQue, I got very different results than what was obtained from an optometrist, and my initial instinct was to think that EyeQue did not work properly.  EyeQue customer service encouraged me to get the glasses and see how it worked.  I did not do that.  EyeQue results closely aligned with the results I obtained from using the advanced technique for testing eyesight.  Getting accurate results requires precision and care, doing exactly what EyeQue requires.  If it is too much eye strain to complete it in one setting, you can stop and continue the testing later.

EyeQue has another theoretical advantage over what optometrists can offer and even I can offer.  With non-EyeQue methods,  vision in one eye must be blocked and only one eye is tested at a time.  That is not the way binocular vision works.  With binocular vision, one eye provides focusing information which the other eye uses to refine its focusing.  As far as I know, only EyeQue takes advantage of that designed feature of human eyesight.  In the testing process, you are instructed to keep both eyes open and focused on something at a distance.  I suggest focusing on something 300 feet away.  In theory, this might also help with some forms of accommodative dysfunction, because when one eye has trouble focusing, help in focusing can come from the eye not being tested.

In theory, EyeQue might also be helpful for those who have lost vision in the central part of the eye.  Non-EyeQue methods require that you look directly at an eye chart.  EyeQue does not have that requirement.

One drawback is that it takes time to learn how to use EyeQue and to do it properly.  An optometrist can not take a patient and provide him with an EyeQue and instruct him on how to do it and  complete the test in the time it takes for a single optometrist visit.

Maybe EyeQue could  be used in combination with a lens set kit and frame.  The eye not being tested could be provided with the most accurate correction for 300 feet possible at this time, and no lens is placed in the part of the frame for the eye being tested with EyeQue.  Maybe the EyeQue could fit through the frame.  This way, in theory, the eye being tested is provided with the best possible focusing information from the eye not being tested.

I have not done a reasonable or good job of comparing the advanced technique for testing eyesight with EyeQue results.  The above review is based on what is remembered and on somewhat flippant observations rather than close, accurate comparisons.

Typical Optometrist Visit

The optometrist may conduct some examinations and evaluations before testing your eyes. He will test for different eye conditions before and/or after testing for glasses. He will ask for your latest prescription for glasses, and he will test your glasses to get your prescription. If you do not have these things, he will do some sort of imaging of the eyes to get an approximation of what your prescription should be.

It is important to know approximately what the prescription is before testing the eyes for glasses. If you do not know what the prescription is, there is a way to get around that problem, but that topic will be covered later.

It is important to note that the optometrist can do some things that you and I can not do. He can test for eye diseases. Testing your own eyes does not eliminate the need to see an eye professional. You may have an eye disease which could result in impaired vision or blindness, and an eye professional will screen for those conditions, so you could be treated and save your eyesight. Eye professionals know an incredible amount about the eye. Some additional information is found at https://www.youtube.com/watch?v=rlLSNeFnv6Q and other web sites.

Understanding the Prescription

If you are a layman testing your own eyes, don't call it a prescription. Call it "eyeglass numbers" instead. If you are an eye professional, you may call it a prescription. Here is an example of some eyeglass numbers:

Right Sphere -0.50, Cylinder -3.00, Axis 94
Left  Sphere -0.50, Cylinder -2.75, Axis 79
Near Vision Add +2.50

What is missing from the above eyeglass numbers? The prism for both eyes. Prism lenses are needed for those who are cross-eyed, or where the two eyes do not point in the same direction. Most people are not cross-eyed, but we sympathize with those who are. We do not address the issue of prism lenses and compensating for cross-eyed vision.

The top row is always for the right eye, and the next row is always for the left eye. The first column is the sphere, or the starting point for how near sighted or far sighted the eye is. It is in multiples of 0.25. The next column is for the cylinder, or how strong the astigmatism is. The cylinder also is in multiples of 0.25. Both the left and right eye cylinders are negative or they are both positive or one of them is zero.

Your lens in your eye might not be completely symmetrical, or your eyeball might not be completely symmetrical. The cylinder corrects for this very common condition. If the cylinder is positive, then the lens has a component that is shaped a little like a cylinder, but only in a specific direction, making the corrected vision more nearsighted but only at a specific axis. If the cylinder is negative, then the lens has a component that is shaped a little like a deflated football, but again, only at a specific direction, making the corrected vision more farsighted but only at a specific axis.

The third column is the axis, which is the angle of the cylinder or deflated football-like lens. The axis is between zero and 180, and zero is the same as 180.

The final row, "Near Vision Add +2.50", shows how much is to be added to the sphere to arrive at a prescription for reading glasses. This number is used for progressive lenses and usually, but not always, is +2.50.

Please note that the same identical prescription can be represented with positive cylinders as well as negative cylinders. Either the cylinders for both eyes are positive, or else they are negative. You can not represent one eye with a positive cylinder and the other with a negative cylinder because that would not be accepted when ordering glasses.

For greatest accuracy, you want to keep the lens combinations when testing as thin as possible in the center of the lens. To determine if you want to convert from negative cylinders to positive cylinders or vice versa, do the math. Add the two spheres together and multiply by two. Add the two cylinders to that number. If the number is positive, then you will need to have positive cylinders. If the number is negative, then you will need negative cylinders.  The interactive guide for testing eyesight does these calculations for you, and the link to the guide is available later on this web page.

To switch the cylinder representation between positive and negative, using signed arithmetic, add the cylinder value to the sphere and that becomes the new sphere. Then add 90 to the axis, and if the axis is over 180, then subtract 180. Change the sign on the cylinder. Do this for both the right and the left eye separately.  The interactive guide for testing eyesight does these calculations for you, and the link to the guide is available later on this web page.

Before testing your vision, it is best to know your pupillary distance.

Pupillary Distance (PD)

Accurate PD measurements are needed when you order your glasses, but precision in the PD measurement is not needed to test your eyesight.  The PD is needed to test your eyesight, because the frame can be adjusted for the PD.  The best way to get the most accurate measurement of your PD is to visit an optician.  Most of them will be happy to do it for free.  Some will refuse, but not many.  Tell the optician you want the PD for single vision distance glasses, to avoid confusion.  Do not state that it is for reading glasses, even if it is.  The PD from an optician will be either a single number, probably about 62, or else two numbers, one for the distance between the right pupil and the center of the nose and the other for the distance between the left pupil and the center of the nose.  If you are in an area that does not have access to good opticians, you will need some other mechanism to measure the PD.  In theory, you could purchase the same equipment opticians use to measure the PD, but in actual practice, you probably could not do it because it is too expensive.  You need a friend to help measure the PD.  The most accurate and cost-effective way to obtain your PD, other than seeing an optician, is to order a PD ruler on-line.  The PD ruler should look something like this:

A ruler like this can be found by searching for "PD Ruler" using a search engine or searching on a site such as Amazon.  I like it because it has a wire which goes right over the center of the pupil, enhancing accuracy.  The ruler is placed over the eyes of the individual being measured, and the nose thing placed on the top of his nose, and the numbers face the person doing the measuring.  The measured individual stares at the top of the nose of the measuring individual, who stands as far away from the measured individual as practical, and adjusts the ruler until the wires are directly over the two pupils.  The pointer on the right is the single number for the PD, possibly about 62.

The reason why the two individuals need to stand as far apart as practical is because we are measuring the distance PD.  Not the near PD.  Therefore, it makes sense to keep distance between the two.  For reading glasses, subtract 3 from the combined PD number (probably about 62), or 1.5 from the left and from the right PD.  For computer glasses, progressives and all other glasses, you use the distance PD, not the near PD.

The PD is needed for two purposes.  One is to adjust the frame, and the other is for ordering glasses on-line.  A frame is like glasses, but where lenses can be swapped in and out to test eyesight.  Do not use the free frame that comes with lens set kits.  Those frames are not very good quality.  Here is the frame I recommend:

The above frame is the CGOLDENWALL Adjustable Trial Frame Optical Trial Lens Frame PD 54-70mm Pure Titanium Optical Titanium Optic Trial Eye Optometry Lens Frame Test Optician TF-BT, https://www.amazon.com/gp/product/B078HZQTK1/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1.  Last I checked, it is not available on Amazon any more, but it is good to check the link to learn more.  I liked it because other good frames are heavier, and this was the cheapest titanium frame of good quality I could find.  It is light weight, which makes it easy on the nose.

There are other good frames that are heavier and adjustable, and those should also be considered, and they are cheaper.  I have a second frame, and I plan to use both of them when testing eyes where there is no prior prescription.  While both frames work in every situation, the frame pictured below works better when testing for astigmatism and there is no prior prescription.  This is because when testing for astigmatism and there is no prior prescription, two cylinder lenses are placed in the frame to be rotated together.  Under these unique circumstances, when using the frame above there is a possibility that the patient would reach for the handle on a lens and, by accident, rotate one of the lenses without rotating the other cylinder lens at the same time.  With the frame below, both cylinder lenses are rotated at the same time, and the risk of that kind of accident happening is minimal.  The instructions to the patient are simpler with the frame below, but it is heavier.  If the frame above is used and this kind of accident takes place, it is readily detected and corrected.

CLICK  HERE  for the interactive guide for testing eyesight.  The interactive guide has been tested, with each component of the guide carefully tested.  This does not eliminate the possibility of imperfections in the interactive guide.