You are not my Optometrist.
August 26, 2017 10:32 AM   Subscribe

There's a part of my eyeglasses prescription that doesn't make sense. I ordered my glasses anyways, and now I fear the glasses I got aren't right.

I recently went to the optometrist, after avoiding it for about 6 years. The result being that my prescription changed a lot. The optometrist gave me a copy of the prescription, which I used to order glasses online (Zenni). However, and I should have paid more attention to this detail before I ordered the glasses, but there's an area on my prescription that I can't figure out. There's something written under the "Prism" field, that I can't make out, and it's not a number, which every source I can find online about how to read an eyeglasses prescription says it should be. Here's a scan of the prescription (all identifying info obscured).

Consequently, when I ordered my glasses, I just ignored that part. Again, I know, a bad idea, but I'm not too concerned because the glasses were cheap, and if I have to order another pair it's not the end of the world. I just received the glasses I ordered, and they are strange. When I wear them, objects that are rectangle or square appear somewhat skewed. For example, when I look at my phone, it looks like this. Same thing when I look at my computer monitor, a page of a book, etc. If I close my left eye while wearing the glasses, the effect seems to alleviate somewhat.

So my question is multi-parted. What is that that's written under the Prism section on my prescription? Assume I'd rather not have to call the optometrist's office and ask, since they were pretty rude about me wanting a copy of my prescription in the first place. I will call them if I absolutely must, but I'd rather get some opinions/educated guesses on what it might say from metafilter first. Is the skewing affect I'm experiencing with my new glasses a normal part of adjusting to new glasses, or did I screw something up by not entering whatever that is in the Prism field. Or is my prescription just wrong?
posted by katyggls to Health & Fitness (5 answers total)
I think the skewing you mentioned is caused by not entering the prism. Zenni has an article about prism explaining what's going on. If you look at the righthand column of that link, there's an 'Ask an Optician' section. I'd send them a link to your prescription and see what they make of it.
posted by gregr at 10:49 AM on August 26, 2017

I'm 99.9% confident that you are NOT supposed to have prism. If you did, it would have to be specified with a number and some other jazz and would likely be different for each eye. The writing on your prescription is probably just indicating no prism, although I can't make out what it says (maybe 'plano'? Although that's not normally what is written in that space)

If you needed it, you'd know -- you would have had a chat with your optometrist about strabismus, lack of binocular vision, or something along those lines, and this would probably not have been the first time.
posted by karbonokapi at 1:03 PM on August 26, 2017

I'm not an optician, but I agree with karbonokapi that it's unlikely you need prism. If the prescription has changed dramatically, you're probably just experiencing the some normal distortion while your brain adapts to new inputs. I had that problem for a week when I switched from distance-only glasses to progressives. The fact that the effect is mitigated when you use only one eye is suggestive.

The effect might be more pronounced if your pupillary distance was measured incorrectly.
posted by brianogilvie at 3:30 PM on August 26, 2017

I have a slight prism and no optometrist has ever discussed with me what it means, as a data point. And I've moved a lot so I've been tested by a few.
posted by bizarrenacle at 4:38 PM on August 26, 2017

Consider: the "prism" field says "Sph". If I were an alien anthropologist, I might guess this means that there is no prism, and that the spherical portion is enough. What shoots that theory to hell is that you have cylindrical diopters and axes marked.

OR, in bizarr-o world, your eye doc somehow chose to write delta as a lowercase (δ), rather than canonical upper case (Δ). In this reading, what was a sloppy 's' in the above interpretation is now read as 'δ'. This also makes no sense, because the stroke pattern is all wrong, and why in the heck would this one person use the wrong case? Also, what are the remaining characters then, and why is "base" empty, when it seems from the link above that every non-zero prism should have a base noted. Who knows. Which brings me to point 3.

This prescription is wack, yo. You gotta call and tell them you need clarification. Be firm but polite, this is literally what you paid them for, and they messed it up.

Finally, you have subtle problem in that your cylinder axis corrections are both very close to 180, but with decently large diopters, meaning (I think) that small errors in the angle will literally skew things. If you have even minor exotropia or stabismus, in my experience, this will be fairly clear to you and others if you look carefully at your eyes when you are starting at a fixed object.

I might demand a whole re-test, because even if they explain the prism thing or it should be absent, you may have a problem with your axes being off.
posted by SaltySalticid at 6:26 PM on August 26, 2017

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