Daily Archives: April 22, 2010

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.