I was wondering if anyone (especially the optometrists here) could give me some thoughts regarding hypetropia. I am, as I understand, an alternating exoptrope with what seems to be  marked hypertropia. I have been undergoing VT for about a year now, and have pretty good convergence, can see some depth on vectrograms and even see the "turbulence" (as Dr Press, I believe, called it--love that) on randot up to 50 on BO and 25 on BI.

My optometrist is reluctant to give me prism for my hypertropia because she feels it is too variable and doesn't want me to become too dependent on it, as she feels some become too dependent on minus lenses. On the Bernell stereoscope, the vertical "issues" do seem to be variable, i.e. I seem to be able to move the horizontal line up and down the horizontal numbers, but am not entirely sure I'm really "moving" the line or just doing some amazingly quick alternations (flickering is what I call it!). When I do wear prisms (not quite strong enough) I sure get a sense of depth much easier and better than without.

In general, if prism is used to correct hypertropia, how does one go about "weaning" off of them? How much time does one spend at one level before lowering the diopters?
I know this is a lot to ask, but I am  just looking for some understanding. My optometrist seems very knowledgeable but, in all honesty, I feel she is very busy and (this sounds bad) don't want to pester her---so thought I'd pester you!!
Thanks for any thoughts, here.

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Very good question(s) Susan, and if your optometrist is as good as she sounds, I wouldn't worry about pestering her.  I tell my patients, as well as my staff, that the only questions you have that pester me are the ones that you don't ask.


Here's a quick primer on hypertropia.  The normal binocular system has outer limits of fusion know as "Panum's Fusional Areas" for which the vertical (hyper or hypo) limits are much narrower than the horizontal.  As Sue Barry describes it in her book, one of the things that helped her achieve fusion was some vertical prism that her doctor prescribed in her glasses and in working through that prism she was able to achiever great overall binocular sensations and stability.  Ultimately as I recall she has been able to reduce the vertical prism but all, as she points out in this Discussion Forum, under the guidance of her optometrist.


Some of us are reluctant to use vertical prism because of a concern about "dependency".  We have worked with a number of adult patients with strabismus in our practice who come to us with vertical prism in their glasses, and we work toward "weaning them off" the prism.  As you might guess, this involves alot of therapy combined with stepping down the vertical prism in the Rx in increments.  Many of the traditional targets used in space, such as Brock String, Aperture Rule, Eccentric Circles, Space Fixator, Walking rails and balance boards can be done with vectors of prism (be they vertical, cyclovertical, yoked, etc. --- don't worry about the terms).


Two final points here:

1)  Your optometrist is well-advised to be cautious about vertical prism, and when you can demonstrate with consistency that that it improves fusion, stability, and function that is a good time to Rx it, and usually in the smallest amount possible that yields demonstrably good results.


2) It sounds like you're using Randot targets on HTS and have achieved great convergence.  Have you used the vertical vergence on HTS yet?


Thank you so much for your reply....you've inspired me to just ask away at my next appt on Wed. To be honest, my hyertropia is consistently present but the degree does seem to change a lot (hyperphoria?--just learning this new language). My optometrist says she probably will give me prism but as minimal as possible and I am appreciative she doesn't want to "overdo it"; I do respect the risk of dependency.

The program I have on my computer is VisionBuilder and I'm not aware of any vertical vergence exercises there.

 I suppost this is pretty normal but it does seem that some days I just can't even do good horizontal convergence and then there are times I simply try too hard on the exercises and lose it all! Again, I am so thankful for this forum to keep me focused (no pun intended---well, maybe) on plugging away at VT and being patient.

My pleasure, Susan.  VisionBuilder is a phenomenal software tool, and has a nice Randot component.  Although it doesn't have the vertical vergence range built in as a variable, you can do use loose vertical prism as a therapy tool while doing Randot target.  I don't want to step on your optometrist's toes since she's doing a wonderful job of guiding you as is.  But if you want to quote me that's fine.  ;)


As an aside, on terminology, technically tropia means the offset between the two eyes fusing is exhibited with both eyes open, and phoria is the position of "rest" when one eye is covered.  But there's a fine line between an intermittent tropia and a high phoria.  Bottom line is, when you're' perceiving the Randot target, you are in the phoric state.  When it disappears you're in the tropic state.

Thanks for the vocabulary lesson :) Unfortunately, being in the "tropic state" sounds pretty good up here with spring still being so far away.......

Despite the blizzard here (gotta love the north!) and getting stuck twice, I made it to my VT appt. My optometrist is filling in for the therapist for now and she remeasured my progress. She immediately noticed that I was using both eyes to look at her more than i ever had before. She measured my vertical phoria at about 9 or 10 diopters and scripted me a 4 diopter lens to wear. She agrees that I am beginning ro fuse more in real life, too (not just on my exercises. I'm excited.....here goes!

Susan, that is fantastic news! (I'm so-00-oo inspired :-) Thanks for sharing. Please keep sharing what ".... here goes!" looks like in the future. Could you start a "fusion in real life" discussion? I'll bet others who have been doing VT longer will join eventually.

I have a bit of an update to my hyperphoria issues. My optometrist has suggested to me to try to correct this (or to get more flexibility in my vertical) by instead of using a base down prism to get my right eye image down to the level of my leftt, to instead use a base up to push the image even higher and work on compensating with an even larger discrepancy (if I got my bases right!). She mentioned that this is a technique Dr Fortenbacher (I think) uses. In explaining the principle, I thought of how I learned NOT to push away a horse who is standing on your foot or else he'll just lean harder into you! Made sense, in a way, to me. I haven't had time to really work with this, but am excited to try. Do you  have any thoughts, Dr F?

LOL, I love the horse analogy. I'm going to remember that next time I have a bad attitude about "loading"! ;-)

Hi Susan,

Hah...I love the horse analogy! Could it be that the horse wants you to pay attention to him/her and so if you try to push away it will make a point of leaning harder to get your attention!?


In what you described, the role of the prisms are to wake-up your visual brain and encourage you to pay attention to and explore. Yes, they make things more difficult, but only if you try to fight it. Instead of thinking too much about the difficulty, try going at it like you are Alice in Wonderland looking for new things. Your doctor and therapist will help you by posing questions that will guide you along a path. The more you explore the "therapeutic path", the more your visual brain will learn and  develop the new neural connections needed to attain normal binocular control...without prisms.

And no... this is not just horsing around! :)

Hope that helps!

Dr. F.

This is a question I was wondering about and would like other opinions (especially an optometrist's?). My new VT is really good, I like her, but sometimes it seems like we don't explain things well to each other--not too surprising considering our 2D and 3D language barrier!

Anyhow, when looking at the Brock string and fusing the bead and seeing the strings crossing, am I "really" fusing if I see the strings both go into the bead but one is consistently just on top of the other? (I am seeing both strings throughout my visual field while doing this). My VT says it's normal, but since I'm sensitive about my hyperphoria, I always thought that I should keep working until I get the two strings to enter the bead side by side and just sort of become one when they get to the bead.

I really appreciate the feedback I can get on this forum. It really helps to hear from all you others who are working so hard!!


I very much sympathize with the challenge that is the vertical trope/phoria. I'll chime in quick with the suggestion that you get both your central gaze and side gazes checked before getting vertical prisms. I don't know how often this happens, but the direction of my vertical deviation reverses between my central and side gazes from a left to a right hyper, which means that efforts to address the vertical with a prism did not work well because neutralizing one gaze exacerbated the deviation in the other. This proved to be a fast track to some unpleasant symptoms.

I've started doing some vertical training, so hopefully this will help. Good luck!

Anna, how interesting that your vertical phoria changes from central to side--wow, I can see that prism would have been quite the trip! From doing the Brock string, (and doing it with my side gaze, too) it seems that my hyperphoria is consistently right hyper although the degree does seem to vary--sometimes without me really knowing why!!


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