A question for Todd.

[chris1213]

Hi Todd,

I remember you mentioned that you experienced double images before having a great leap improvement towards emmetropia.
I wonder, were the double-images you saw, on top of everything around you or only from bright objects like stop lights, the moon and so? Also, how did you experience it, you would just see them or it was when you opened your eyes a little bit that they would appear strongly?

The reason I make this questions is that every time I am opening my eyes a little bit, kind of like having control over my eyes, I see a double perfect image on top of lights, but I still haven't read of anyone who has had the same thing and I'm not sure if it's only astigmatism. If I look at the Snellen Chart and also kinda open my eyes the 20/20 line becomes way sharper. So I would like to hear about your experience with double image.

Chris

PS: I don't recall having experienced this on the past months, it's recently that I've noticed it.

[Todd Becker]

Chris,

The double images that I experienced were mainly in looking at distant objects which have contrasting sharp lines or edges.  Examples would be overhead telephone wires, tree branches, sign posts or edges of buildings.  I would experience these double images only on distant objects beyond my focal range.   

While the typical objects were dark lines or edges against bright backgrounds, I did also experience the reverse by looking at the tail lights of cars while driving.  I would also see the sharp red tail lights with a double-image of a blurred red tail light.

What I found was that the two images were not equivalent -- there was always one that was much sharper, one that was blurry or diffuse.  I would consciously focus on the sharper of the two images, and over time that image became stronger and the blurry image became weaker.  It is also important to point out that these double images occur in a single eye, while patching the second eye.  Therefore, they cannot be a result of some mismatch between the two eyes.

I proposed an explanation for the double images on my Rehabilitation page.  As I said there, I have no proof for it, but it is consistent with my experience and my understanding of the IRDT theory of myopia and myopia reversal:

But there is one more mystery:  how to explain the transient “double vision” of focused and unfocused versions of an object that arise in the process of adaptation?

Again, for this explanation we turn to the science of neuroplasticity.  The retina is not single plane, but rather a tissue of some depth, consisting of multiple layers of sensitive photoreceptors cells (rods and cones) and intermediate conductive fibers. In fact, the photoreceptors perversely evolved for various reasons to be at the back of the retina, with the “wiring” actually in front of them.  But the photoceptors are distributed over multiple layers. Presumably, the most active receptors are those which are usually stimulated by well-focused images.  After all, those are the ones whose signals the brain can interpret, and they receive the most reinforcement.  For a myope, these will tend to be the receptors in the focal plane of close objects, toward the back of the retina. Because the myope is doing a lot of close work and spends less time looking in the distance, the closer retinal cells get less stimulation and suffer from underuse.  However, if these closer layers can gradually get more stimulation, or example by using plus lenses, they will adapt to increase in sensitivity and the strength of their signalling to the visual cortex will gain prominence.  At some point, weak signals from this forward layer (on which there is a sharper image) will be sent simultaneously with the stronger signals form the backward layer (on which the images are blurred).  During the period of adaptation, activation of multiple layers will be perceived as a double-image. Eventually, and with time, the sharper forward layer will dominate over the backward blurry layer.  And as the overall shape of the eye is remodeled as the eye grows in response to focusing on distant objects, the focal “strain” on the eye will be reduced, and a new equilibrium shape will take hold. This hypothesis is unproven, but is consistent with known mechanisms, and could be tested experimentally.

I'd be interested to learn more about the details of your experience with double images.

Todd

[OtisBrown]

Hi Todd and Chris,
Subject: Some additional details and the "scare factor" of the word Diplopia.

The term for slight ghosting (that is seen by people with normal eyes), is called "Diplopia".  I understand from a detailed study by Dr. Guyton, that about 20 percent of the population has this normal ghosting, but they never notice it.

Here are some of the details.

http://emedicine.medscape.com/article/1214490-overview

It is clear that some people, starting at 20/60, had this "Diplopia", but it was covered by the fact of the blur that they had.  As they work with the plus, on a continuous basis, and begin to clear the 20/30, 20/25 and 20/20, line, they begin to "see" things they never could have seen before - because of there intense interest.  In fact Chris states that he sees the 20/20 line, now, presumable as a "flash".  In addition, Todd saw the same thing - as did Mr. Severson.

I personally look at, and count the number of letters I read on my Snellen chart, it is not just that it "looks sharper" - which is truly a subjective judgment.  It is that I objectively identify the letters, to confirm I pass that line.

As always, objective Snellen clearing (by wearing a plus for all close work), is not easy.  But it is good that we have an "open forum" so we can discuss these transcendent "fears" we might develop about wearing a plus to achieve our objective goal.

For those successfully working with the plus - this subject will come up many times.  Here is some more analysis by Dr. Alex:

http://frauenfeldclinic.com/reminder-tip-recognize-double-vision/

As always, I would prefer to have 20/20 (self checked) with slight ghosting, rather than to get serious myopia, induced by a strong minus worn all the time when I am at 20/50.  For me, that is my "trade-off" in the way I value my distant vision.

[Todd Becker]

Otis,

Thanks for the good links -- and for providing the the term "diplopia".   

I did a little digging and found that while binocular diplopia is a cause for concern because it points to problems in the brain, monocular diplopia (double vision or ghosting within a single eye) points to phenomena within the eye that are quite common and usually benign.  Yet OD's often assume that diplopia is binocular!

Here is a very nice article by Stephen Archer about diplopia, from which I've excerpted some relevant quotes.  It explains a condition called "physiological diplopia" which almost everyone has to some degree under certain conditions, and can be easily demonstrated by simple experiments.   Archer proposes a theory of physiological diplopia based upon normal optics of diffraction under conditions of slight defocus.  I intend to spend some time going through the paper, but at first scan it is quite compelling:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2258122/

Monocular diplopia or polyopia can be experienced by almost everyone under certain circumstances. Phenomena such as the doubling of the horns of a crescent moon, splitting of a fine white line on a black or a black line on a white background—all made more pronounced by defects of focus—have been repeatedly mentioned in the literature over many years. Monocular diplopia accounted for 25% of diplopia cases presenting to an ophthalmic casualty department. Yet when presented with a complaint of diplopia, clinicians often overlook monocular causes, presuming the problem to be of binocular origin.

Although it is usually subclinical, being either unnoticed or regarded as a normal state of affairs by those who observe it, the most common monocular diplopia is that occurring in otherwise normal eyes, with or without refractive errors.

Fincham stated that physiological monocular diplopia occurs in 40% to 50% of otherwise normal eyes. It can be cause for clinical complaint but is usually so minor that only the occasional highly perceptive patient with otherwise good vision will remark about it spontaneously. Most individuals are unaware of it until it is demonstrated to them under special testing conditions. A bright line on a dark background is a particularly effective stimulus for eliciting physiological monocular diplopia, which is characterized by a faint secondary image that is displaced 3 to 6 minutes of arc upward from the primary image.

In a study of 70 individuals with normal visual acuity, Fincham found that differences of 0.5 diopter or more in refractive power between the upper and lower portions of the pupil correlated with the observation of this form of physiological monocular diplopia.

I'd be interested to get some feedback on Archer's theory of diplopia.

Todd

[chris1213]

Todd and Otis,

Regarding the link Otis shared I think I might be experiencing Polyplopia ("...the perception of more than 2 images [...] often a monocular phenomenon caused by refractive aberrations resulting in multiple images of one object.") I see a double image with most bright lights but with further objects, like the moon, I see a sharp second image but the moon also appears to have other "layers" around it.

It did catch my attention that the website said:

Causes of polyplopia include irregular corneal astigmatism, lenticular opacities, multifocal lenses...

So it might be normal to have Diplopia but the Polyplopia I experience might also have to do with the degree of astigmatism I may have. However, I intend to keep working on the plus lenses to improve my vision.

Also, Otis, you're right when you say:

It is clear that some people, starting at 20/60, had this "Diplopia", but it was covered by the fact of the blur that they had.

That's exactly what I thought, that the reason I might not have noticed it before was because I saw more blur than sharp images but now that I have a lower case of myopia those double images have become more evident.

Anyways, thank you for your replies,

Chris

[Myoctim]

Some time ago someone posted those double images would shift their position when tilting his/her head.

Now after me also experiencing double vision again I did a check and indeed, the fainter image moves up when tilting my head towards my shoulder and vice versa.

Any explanation?


 

[Alex_Myopic]

Do these double images go away when wearing full prescription glasse? If yes then they are due to refractive error (myopia). Maybe the brain tries to compensate for some not refracted well in the retina pictures but a few stay.

[CapitalPrince]

I also have slight double vision due to astigmatism. I know its astigmatism because i wore glasses with astigmatism before. However with both eyes I see some "ghosting" and its very annoying especially with street signs and streetlights. With a -0.75D lenses I see no double vision or haloing for some reason. I can exceed the 20/20 with a -0.5D. With a plus lens the double vision or ghosting is very very evident and annoying. 

Did anyone has success in eliminating or reducing their double vision or ghosting?

[Alex_Myopic]

Hi CapitalPrince,

here is some analysis and solutions to astigmatism

http://frauenfeldclinic.com/category/astigmatism/