Why is my depth perception better under cycloplegia, or when I’m tired and not wearing my prescription?

Dear all, 

I have some questions regarding depth perception and because I like the discussions on this forum, I decided to post some. 

But let me introduce myself first, as I'm new on this forum: 

I was diagnosed with strabismus in early childhood (esotropia, that might have been pseudostrabismus) and had surgery in both eyes at the age of 5. I wore patches before surgery, that taught me how to ignore the vision in one eye. After surgery the only VT were daily 5 min pencil push ups, which I did with the correct eye motion, but without the accompanying correct perception. My left eye was (is) dominant, the vision in the right eye was ignored, but both eyes have 20/20 vision (no lazy eye). Cosmetically the eyes looked straight with alternating exotropia. Stereoscope testing (bird in a cage) failed as I could not see the two images simultaneously, but alternating. During primary school I used the left eye to read and do close work, without any problems. Sport concerning catching balls was not my favorite. They also told my parents that the period of plasticity had closed and the cosmetic effect was pretty good and that, although depth perception was not present, no further follow-up was recommended at age 12.

In secondary school my left eye’s vision became worse (S-2,00), but the optometrist (not specialized in strabismus) refused to correct the refraction as he said that it would be handy to have one eye for close work and one for distant viewing. So I learned to read the blackboard with my right eye (which took some minor, but noticeable effort), alternating with my left eye in case things got closer.

But after a near accident while driving a car, I was sick of not seeing 20/20 with my left eye and went to another optometrist and bought full prescription glasses (in the mean time the right eye also got slightly worse, and over time and a cylinder developed), in the mean time happily alternating with preference for the dominant left eye with the right eye rapidly taking over in case the left was obscured or had blurred vision for one reason or the other.

For years I took this for granted until my latest prescription glasses with

Right S-2,00=C-0,50 Axis 148; Left S-2,00=C-2,50 Axis 155 drove me crazy as the alternation was much more present and annoying, resulting in a bloody red left eye at the end of the day. I went to an ophthalmologist who performed a covertest:

(30 cm slight exophoria with left hyperphoria +DVD, 5 m slight exophoria with right hyperphoria +DVD), tested my eye movements, which were intact and also the Titmus fly, Animal A and concentric circles (until 2) test was positive, indicating that some depth perception was present. Congenital nystagmus was latent. She did not have an explanation or solution for the asthenopia.

Just after the examination, during the bike ride to work, I noticed that under cycloplegia, I could suddenly fuse the two images from both eyes and that I had some depth perception, although my vision was heavily blurred. This effect disappeared after I regained my normal non-cycloplegic 2D vision.

Now that internet has so much info I started a study and found out that the asthenopia probably was caused by anisometropia and the resulting prism effect in the glasses. So I switched to contact lenses, which was a great relief, and started more internet research on depth perception and how to improve it.

As in the Netherlands no VT like in the US is available, I tried to figure out what exercises I could do to improve depth perception, read Sue Barry’s book, made a Brock string, bought red-green glasses and designed some powerpoint/Matlab based VT exercises.

I discovered that I can fuse quite well, although I never tried it before. I can see the magical Brock string X (although the lines cross a little in front of the bead at all distances). In dissociated situations, ARC is present in varying degrees.

I improved my depth perception from nothing noticeable in daily life, to some peripheral depth perception (0-1.5 m distance). In stereograms now I can see only the largest disparity portion of the image, but not the details. The up/down part of the ARC nearly disappeared.

 I still have many questions like:

- Why is my depth perception better under cycloplegia, or when I’m tired and not wearing my prescription?

- How can I improve my central vision depth perception (as I appear to alternate rapidly, or suppress the central portion of the visual field even though the peripheral part of the image is neatly fused)?

- How to get rid of the remaining ARC?, Especially in upgaze I have double vision when I use both eyes together. 

Views: 249

Replies to This Discussion

Permalink Reply by Lynda Rimke on October 31, 2012 at 12:38pm

Hi Yvette,

Welcome to Sovoto. I am another adult patient with a whole different set of challenges. I read your case with interest (and wikipedia handy to help me with the terminology!)

I do hope that several optometrists comment and offer theories or better yet definitive answers to your constructive questions.

I also have more questions for you:

Is the X in the string blurry and the bead in focus?

Is your contact prescription the same as the most recent script you are having trouble with?

Were you wearing any prescription when you were cycling?

Is your lack of ability to accomodate due to age (presbyopia)?

I'm looking forward to others' comments on whether ARC affects accomodation and clear fusion ...

Permalink Reply by Yvette on October 31, 2012 at 3:17pm
Hi Lynda,

Thanks for your reply, I'll try to answer your questions:

The x is blurry and the bead in focus, when I try to focus on the x, it moves towards me, away from the bead (overconvergence?). If I try to relax my eyes, the x moves towards the bead, but then the bead is blurry as well. I cannot uncross the end of the string, as if I cannot move my eyes more outward. Which is strange because I can fuse quite wide parallel view stereograms.

The contact prescription is the same. But because the lenser are closer to the eyes, the distortion due to the difference in refraction is said to be less compared to glasses.

I think I was wearing my glasses while cycling, but the vision was so blurred that it made no difference (although I could see the traffic lights and cars :) )

In general, I have no problems accomodating, and no presbyopia. Switching between close reading and reading distant texts is no problem.

I'm looking forward to some comments.
O, and if anybody can recommend me a Dutch VT, I'm quite happy.
Permalink Reply by Robert (Bob) Hohendorf OD on October 31, 2012 at 5:43pm

Hi Yvette,

   I personally know Optometrists that do VT in Denmark, Norway, Switzerland, Sweden and Germany. I am sure some of them must know some good VT docs in the Netherlands. I will check with them if you want me to. Where are you located in the Netherlands. 

   It sounds like you can see single with fusion and can see clear, but can't see single and clear simultaneously. A good therapist or guide should be able to help you through these issues. The positive thing is you can do both seperately, many who start down the VT road succesfully cannot at the begining.

   When two eyes do not work together in all phases, as your eyes did in early development, you have three defenses to deal with your lack of two eye coordination and double vision. Blur one image (which you did after your surgeries), Move one image (By turning an eye which you did very young) or ignore one of the inputs (which you probably did at an early age, but have figured out how to do again).

 

   Your central suppression issues are their to protect you from seeing double more often. They can be worked through as well when the undrelying reason you learned how to alternate centrally is taken care of. 

 

 

 

Permalink Reply by Robert (Bob) Hohendorf OD on October 31, 2012 at 5:51pm

Sorry. I hit the send button before I was finished and proof read my spelling errors.

   The ARC issue is one I am not sure you have to deal with. I am not sure it is there in your case, but you would need someone to test that.

   You sound like you are close to getting your eyes aimed and focused together, but when you want to see clear you loose alignment and when you quite trying to see clear (tired) or or forced to not focus (cycloplegic) you can see single. These are pluses in my view of your ability to eventually get both at the same time.

  You need some professional help in getting your "what is it" and "where is it" systems to coordinate at the eye and the brain level. 

  

R A Hohendorf OD 

 

  

Permalink Reply by Yvette on November 1, 2012 at 3:37am

Thanks, Robert, 

I'm in the The Hague/Rotterdam area. 

Permalink Reply by Emanuele Ziglioli on April 27, 2013 at 6:01am

Hi Yvette,

how's it going? I don't understand some of the terms in your post.

What's the meaning of "cycloplegia" in this context?

(nothing to do with cycling, more with cyclops, right :-)

What's a "cylinder", a type of astigmatism?

I see you code in Matlab, you may be interested in learning and/or taking part with this project: http://3d4amb.unibg.it

Permalink Reply by Michael Lievens on April 27, 2013 at 9:18am

Hey, Yvette! In Holland they are further along in accepting behavioral optometry than in Belgium and I found they even have a site uniting all practitioners in the Netherlands: http://www.info-fo.nl/content/. In case you would like some assistance in your quest. :)

Now as far as I can tell from my own experience it makes sense to me your vision relaxes when tired or cycling. When you are in control your brain resorts to your usual strabismic eye habits but when tired you lose some of this control and you 'slip back' towards more natural binocular vision. Because it actually takes more energy to keep the strabismic system working, even though that is what you have been accustomed to since forever.

I think it's awesome you already experience some stereo vision. So there is definitely something to work with... There are plenty of low tech exercises to work on this... I work a lot with red green glasses and complementary tools, cross eyed three D pics, prism flippers... But I'm coming from double vision so it offers a different vantage point to dealing with the matter than in case of suppression.  In my experience, the hardest thing is to be patient while keeping at it.

Veel succes nog en ik hoop dat je al verbeteringen hebt ondervonden sinds je dit hebt geschreven!

Permalink Reply by Yvette on April 29, 2013 at 9:58am

Hi Michael, 

Thanks for the Dutch list, I tried one of them, but it was a bit disappointing as they are concentrating on fixation disparity and reading (dyslexia) problems.

Although the fixation disparity is clearly present in my case, I don't have reading problems at all (I used to read with only one eye, now I can use both).

The up-down part of the fixation disparity could be reduced with a prism, but the left-right part changed a lot during the test: no stable value could be determined (can this be due to prism adaptation???). 

They were a bit preoccupied with the idea that I have a limited peripheral vision (which is not the case and it was not measured at that time) and that the best therapy should be color therapy, an approach that for me (a rational physicist) was a bit too holistic. They offered it no cure no pay, which I found reasonable, but the definition of 'cure' was very very vague, something like: "you'll be more aware of your vision".  

Maybe I just chose the wrong one and should I try one of the others. 

So I decided first to do a literature/internet search to see if there is a more scientific approach and I found a lot of information. In the mean time the up-down fixation disparity (almost) disappeared and my first depth perception appeared. 

Still I'm interested in some advanced vision therapy that concentrates on improving depth perception, if that is available. 

 

Permalink Reply by Yvette on April 29, 2013 at 6:53am

Hi Emanuele, 

Thanks for asking, I'm still improving, with a slow rate, but noticable on daily basis! I can say now that most of the day both eyes are "on" and this leads to some depth perception, I experience no double vision, but this is due to the central suppression which is still present in varying degrees. 

I use hidden image stereograms now to monitor the progress and it appears that in case the disparity between the images is too small or too big, I loose depth perception, but this is also improving slowly.

Considering the terms:

Cycloplegia is paralysis of the ciliary muscle of the eye, resulting in a loss of accommodation. Cycloplegia with accompanying mydriasis (dilation of pupil) is usually due to topical application of muscarinic antagonists such as atropine and cyclopentolate.

Cylinder indicates the amount of lens power for astigmatism: The term "cylinder" means that this lens power added to correct astigmatism is not spherical, but instead is shaped so one meridian has no added curvature, and the meridian perpendicular to this "no added power" meridian contains the maximum power and lens curvature to correct astigmatism.

In my case the astigmatism axis is not 90 or 180 degrees, but has an oblique angle (160 degrees). 

The Matlab project seems interesting, I'll check it out. 

Thanks!

Permalink Reply by Emanuele Ziglioli on May 3, 2013 at 11:52pm

Thank you Yvette for all your answers.

You're obviously very knowledgeable, are you self-trained or have you taken some papers in optometry or vision in general?

I like scientific approaches, and hate the way the word 'holistic' is misused, but sometimes other approaches can be effective for somebody at least, so I keep reading and hearing about those experiences.

I'll send you a PM so we can carry on a scientific conversation offline, if you're keen :-)

Permalink Reply by Yvette on May 7, 2013 at 5:57am

Hi Emanuele, 

I read all the papers I could find on the internet... So self-trained more or less. As English is not my mother tongue, I use the scientific terms that I learned from these papers (just because I don't know the daily life equivalents ;) ) with the help of wikipedia and google. 

Like you, I'm curious about other approaches as well, but for me it depends also on how they are presented ;). 

Permalink Reply by Naoise McMullin on May 21, 2013 at 5:27pm

Hi Yvette

I've read through most of your posts and wondered, if you managed to  find a VT in the Hague, or are you doing things on your own? I thought it was interesting that you saw depth when you were tired; or was that more when you weren't trying so hard, and maybe not looking for details, etc.? If you're working on your own, what else do you do, besides the stereograms? I agree, one shouldn't analyse one's vision for depth, as all you'll "see" is what your analytical mind tells you to look for, ie depth according to Cartesian coordinates or 2 & 3 point perspective, which is not at all what one wants.

Re:

- Why is my depth perception better under cycloplegia, or when I’m tired and not wearing my prescription?

- How can I improve my central vision depth perception (as I appear to alternate rapidly, or suppress the central portion of the visual field even though the peripheral part of the image is neatly fused)?

I don't really know, of course, but it seems to me that, when we look in terms of seeing acutely, we "over-fixate", that is, over-emphasise the very centre of vision (the foveal or macular area). Many people on this site seem to be more or less obsessed with achieving stereo vision in the macula area first and foremost, which is unfortunate,  as this is the hardest and unnecessary for most real-world perceptions of depth. In my view and experience, depth is perceived when one "disengages" the foveal vision, and sees with both eyes over the area of the retina that lies immediately around or outside the macula area. The practice I have read about of developing binocular vision from the peripheral in towards the centre is a far more sensible one than the (Brockian?) one of starting at the very centre. In the exercises I do, I either make the centre the same for both eyes (and start with something relatively large, then as I get better make this smaller), leaving whichever eye is dominant to  go on being dominant there if  it wants to, or I make the centre "of no significance" -- ie just blank white space or some other thing that is not detailed and not interesting. This helps to turn the mind away from acuity and the foveal vision, and more towards the less acute but interesting "peri-foveal" vision. (I don't know if "peri-foveal" is a term, but by it I mean the central area of  the retina, outside the foveal area.)

Naoise

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