Prism lenses



[Photo is of me with new glasses on.]

So at my last eye exam (where I also have a way stronger prescription than before) the guy finally noticed I was seeing double. I had gotten to where I really had to concentrate to tell if I was or not because it’s been that way so long when my eyes are relaxed. (I had even bought an eyepatch for days when I really wanted single vision, and other times taken to closing one eye a lot. And I had no idea you were supposed to tell eye doctors about seeing double. I said I did once when my regular doctor asked and he never mentioned glasses.) And then he did a bunch of tests to see how far my eyes swing between double and single eye vision, told me I had exotropia (eyes that point outward from where they should, in my case both eyes), and prescribed prism lenses.

He told me it would feel weird when I got them on. And it did. Things sort of converged and then diverged in the other direction and swung in and out back and forth for awhile. Rapidly. Then it got so I was seeing single except if I relaxed too much. But the woman at the glasses store said that should change in a few days.

The hardest part to deal with, though, is the depth perception. I’m used to not having that. Even my tinted lenses didn’t help it this much. But it made my trip home completely terrifying.

I never knew how high off the ground, and therefore prone to tipping sideways, my powerchair was. There were all kinds of bumps in the sidewalk and missing tiles and stuff that look huge, I used to think they were quite shallow. At one point I overcompensated and drove my chair into a position where I was sticking out into the road and my wheels were spinning on air. (Thankfully a pedestrian helped me.)

I got home very carefully and nervously. I was constantly distracted by stuff sticking out at my face, noticing relative tallnesses for the first time, and really disturbing-looking bumps in the sidewalk. I used to navigate largely by feel, using sight just for crude measurements of where to go. Now sight was so accurate it was some combination of distracting and unnerving.

They have all told me it is a terrible thing to switch between prisms and regular lenses. So I am not doing that. It is weird though to take my glasses halfway off and see that something is double outside the glasses and single inside them.

So that’s all I know so far. They say it’ll take at least a few days before I finally get used to them. I hope I get used to having depth perception because running around outside seems fairly hazardous until I do. Things that I’ve done a hundred times by feel are outright scary now that I can see the size of some of the sidewalk cracks. I wonder how many of my visual problems are related to this, and how long I’ve had it.

About Mel Baggs

Hufflepuff. Came from the redwoods, which tell me who I am and where I belong in the world. I relate to objects as if they are alive, but as things with identities and properties all of their own, not as something human-like. Culturally I'm from a California Okie background. Crochet or otherwise create constantly, write poetry and paint when I can. Proud member of the developmental disability self-advocacy movement. I care a lot more about being a human being than I care about what categories I fit into.

18 responses »

  1. I’ve been though similar when I got my first glasses too! I don’t have double vision but the fuzziness in my eyes made it harder for my brain to perceive depth. I never really realised how flat the world looked before my glasses but when I first put them on the world “popped” into 3d and it was quite surprising.

    I think I spent most of the day taking on and off my glasses to see it go between flat-ish and “jumpy-out-ish.”

    And yeah, having much better depth perception does help picking out objects, at least for me.

  2. Yeah my glasses were in huge need of updating too (I couldn’t see Venus in the sky with my old ones, which is when my friend told me to get my eyes checked), enough that it surprised the eye doctor.

    And the popping out effect is weird. The first time I ever saw stuff pop out like that, I had had good vision but terrible depth perception (bad enough I nearly got myself killed a few times), and somehow hallucinogens gave me temporary depth perception (at the time I assumed that’s what my fellow drug users were yammering about when they went on about seeing into other dimensions (facepalm)). The second time was when I got my first pair of custom tinted glasses. And this is the third time, and the most extreme out of all of them.

    The three things that really got to me today were how high off the ground my chair is, the size of the sidewalk cracks, and tree branches. I swear the trees looked like they were going to poke me in the face. And wow… the litterbox is 3d too. It’s like a 3d movie only in real life, and I can’t yet tell if I like it or not. Normally my visual perception is so crappy that doctors who’ve only been given three choices to rate my vision have marked “low vision” even when I was corrected to 20/20 (because there’s no space for “sees well but can’t make sufficient sense out of it”). And this seems to be… not a total improvement, but a huge enough one that my brain is kind of wibbling and doesn’t know what to do with it yet.

  3. My left eye’s astigmatism was small enough to pass undetected, yet serious enough to leave me without depth perception. Getting it corrected by my new pair of glasses was amazing. I remember looking down at my hands on my keyboard and suddendly seeing 3D – the depth of the spaces between the keys, my hands floating over the keyboard, obviously at a distance from it…it was enough to give me vertigo. After a couple of days, the unusualness of depth perception faded. I still had it, but it no longer pulled so urgently at my attention and I could go about my day without having to stop to look at the pretty 3d images more than a couple of times a week.

  4. When people get new lenses that are quite different from what they have had before they are often warned to be extremely careful going down steps etc. as they may misstep. It does take several days to adjust. For me I remember when my astigmatism was adjusted for and at first my brain didn’t interpret things right and everything looked a bit warped but then within a few days everything looked normal. For sure be extra careful about any excursions until your brain adjusts to what your eyes are seeing. You are like almost going from 2D to 3D and that has to seem really unsettling. Your entire body will have to adjust to what the difference in spatial perception means. Good luck with that. I like the color and shape!

  5. Isn’t it WEIRD?

    I’ve got prisms, too. Got them a few years ago. I kept having to turn my face to scoot past things the first couple weeks, because they really did look ready to jump out and trip me.

    Now I get migraines like woah when they’re even a little crooked. Silly acclimation.

  6. I’ve never had an experience quite as dramatic as this, though I do remember that one of the times I got a new eye glasses prescription it took me a few days to get used to how clear and sharp everything suddenly looked.

    I read once about a blind woman who had surgery to give her vision. It took her a long time to get used to it. In the early days, there was apparently one occasion where she gave up walking somewhere, went back home to get her guide dog (who she still had), closed her eyes and went out again but relying on the dog to guide her. Walking with her eyes open, with her new vision, was making her very dizzy. It was scary to see things seem to move around her so quickly as she walked, including the sidewalk under her feet.

  7. I’m reminded by your post of the way that movies portray people who suddenly gain sight–as though they just wake up one day after being blind all their lives and dance instead of being absolutely terrified. I’m also reminded of a story of a man who had lived in the rainforest all his life and was brought to the edge of a cliff. Instead of being amazed, he broke down and cried; he thought that some catastrophe had occurred and that everything before him had become miniaturized, because he wasn’t used to looking at such great distances.

    It takes a lot of courage to see differently. I hope you’ll find the world even more interesting and beautiful through your new glasses once you become accustomed to navigating.

  8. We found a pair of sunglasses with some kind of reflective coating, at some point, that had the effect for us of giving sudden depth perception we’d never had before. I don’t know if it was as large and major a difference as the one you describe, but… we spent several weeks experimenting with putting them on and then taking them off and putting them on and taking them off again, to see how they made things look different, the strangeness of how things popped out at us. The depth was really weird, at first. It initially felt like a novelty, like how we used to put prisms up close to our eyes as kids to see how objects looked different through them– a similar kind of perceptual game. Or maybe even more accurately, like old stereoscopic photographs, which used to be one of our big perseverations. It was just like the way the images suddenly popped out of the flat photographs. (According to some people, we apparently “shouldn’t” be able to see stereograms well because our depth perception is so bad, but we’ve been seeing them in wallpaper and things ever since childhood.)

    But… anyway, at some point, the question of “is this how most people are supposed to see the world all the time?” came into our head. The more we wore them, the more the world without them started to seem really flat and depthless. It eventually got to the point where we put them on every time we went outside or got into any kind of moving vehicle, and after getting used to seeing things in depth for a long time, we started to get really, really disoriented without them. I think it was/is one of the contributing factors to why the whole suddenly seeming to become “more autistic” happened to us in our mid-20s. We’d always had a tendency to see objects as collections of parts rather than whole things, and the sunglasses (which we still wear) made us see them as more whole, although this wasn’t always good– sometimes we prefer to take them off, if we’re just sitting still, and see the world come apart into shapes again.

    The one thing they really don’t help with is reading, and our brain’s tendency to parse words as being just shapes, which it can usually connect to sounds but not as often to meanings. (This seems to have been why we were able to test as having an “adult reading level” at the age of 8 while often having absolutely no idea of the meaning of what we were reading.) The only thing we’ve found that seems to help with that at all is tinted overlays. Is it possible to get prism lenses that are also tinted, or is that just not possible given current technology?

  9. I’ve never tried prisms unless you count those thin plastic cardboard-framed things that make everything look rainbowy (I got some in the gift shop of a science museum, or something, as a teenager). But I did have a weird experience with depth perception and glasses as a kid. They actually gave me bifocals for a while because I read a lot and they (eye doctors) were worried about my distance prescription causing eye-strain for close range stuff. Eventually they decided to give me regular (non-bifocal) lenses again, though (maybe a year or two later) and after that things were VERY weird for a while. I very nearly jumped out of a tree from a rather dangerous height because the ground looked much closer than it was.

  10. I don’t fully understand the science of this, but these sort of prisms don’t make rainbows, they just move the images over somehow. So that instead of being two separate places I am seeing, it’s just one. You can have different degrees of prism in different directions to deal with eyes that are pointed in various directions when they shouldn’t be.

    Today I do feel better than yesterday but the stuff popping out effect is new and strange. I don’t dare go out far until I’m more used to it than this.

  11. I am thinking your body needs to react to the world as you now see it for a period of time and make adjustments. It is like a baby learning that when you reach for something you actually connect with it. It takes some experimenting before it feels right. A good deal of a babies first work in crawling about is integrating sight with body sensations and it takes time. Once your body interacts with the spatial feeling of the image of things sticking out all over the place where they didn’t used to that will begin to feel more natural. It is not something most of us have to do as adults so it must feel odd for sure.

  12. I have no depth perception either as a result as CP related strabismus and whatnot. I’ve had the muscles surgically corrected twice but the loss of depth perception is permanent. I’m constantly walking into puddles because I can’t distinguish them from the ground. It would be interesting to suddenly gain depth perception like that…sounds freaky.

  13. I’m reminded by your post of the way that movies portray people who suddenly gain sight–as though they just wake up one day after being blind all their lives and dance instead of being absolutely terrified.

    There was the one Val Kilmer movie (At First Sight) which dealt at least slightly realistically with how all of the visual information would seem confusing and nonsensical at first, and how it would be a lot of time and work to make sense of it and learn to understand the meaning. (It also mentioned the complication in employment terms caused by going from being unable to read print because he couldn’t see it, to being unable to read print because he didn’t know how).

  14. I just got some new glasses. I love them – the world is clearer, but…at the same time, distances and perspectives seem strange. It’s taking my body a while to adjust – today I just crashed into a rock and messed my knee up bad.
    Take care, take it easy until you get used to them.

  15. Oh! Prism glasses! I’m fortunate to have double vision both sideways and vertically, and it’s different near and far. The first couple eye doctors didn’t believe it!

    It always takes me a wearying 14 to 20 days to become accustomed to a new prescription.

    And then, sadly, after a year or so my vision changes again and I need the prism changed.

    My latest eye doc did teach me something fascinating. There’s a psychological “comfort zone” for vision: anything that’s closer than that makes one feel uneasy, and then closer still can make one feel threatened. The eye doc claims that many people DXed with “reading disabilities” actually are dealing with this “too close for comfort” issue. If a person’s natural focus point is “too close,” then why would they want to read? She claims that one can oh-so-slowly bring the comfort zone boundary closer to one’s natural focus.

  16. I have astigmatism since mid-childhood.
    About two or three years ago, I got new glasses, and chose a new type of lens that was flatter in front than anything I’d ever had before.
    Wow. I had known I had a problem with seeing object moving directly towards me, or calculating how fast said objects were moving. Only after I got the new lenses did I realize why: I had only partial depth perception.
    I can see fully in depth now, but my brain still has trouble processing, since I went for so long without that part of the visual field.
    The only amusing side effect of that visual limit is my brain learned to calculate 3D from an otherwise flat image. If a tv is sharp enough, I see in 3D whether a program is in that format or not! =)

  17. Luckily my vision stapped to go worse at 20, therefore I’m just having -3 dyopters in the left eye and -4 in the right eye, plus a -0,25 and +0,25 of astigmatism, both in my right eye (but it bothers me a lot, at the point that I perceived it like if I’m having 2 dipopters. 0,25 is right, because with my glasses, I see clear). I might have astigmatism in my left eye too.
    Recently, my optician didn’t visited me accurately, and he gave me lenses with just -2 and -2,75 diopters, and left astigmatism uncorrected. I wore my new lenses two days, but blurriness (from myopia) really bothers me. So I went back to my old prescription (luckily last time I bought two pair of glasses).
    I have myopia since I was 12, astigmatism since I was 21

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