Could pupil dilation be the cause of my inaccurate eyeglass prescription
May 16, 2013 7:04 AM   Subscribe

The last two times I got a new prescription the first try was way off. Could this be due to the eye drops? Or is it just communications?

I am extremely myopic and have astigmatisms in both eyes. (I'm not going to pretend I know the right terminology for all this stuff.) I had an exame a few weeks ago, took the prescription to my optician and ordered two new pair of glasses to replace the ones I have: one pair of bifocals for distance & computer screen, a second pair for computer screen & reading. The new distance glasses were fitted yesterday, and they were a disaster: I couldn't read three inch lettering from 15 feet.

I had a similar issue the last time -- same doctor. It cost me less that time because I was only getting one pair of bifocals. That time, the ophthalmologist basically presented it as a communications problem -- I didn't explain what I really wanted the lenses for. I get really agitated with issues relating to my eyesight, so I don't remember clearly why I didn't challenge this.

It's occurred to me since yesterday that the issue could be due to dilation. I remembered that my vision is extremely poor after I've been dilated. I can't focus on anything -- can't read road signs at all (meaning, even very large print ones), and dark glasses are very little help. I basically have to plan on not seeing anything much for several hours.

Is it possible this is the reason for the bad prescriptions?
posted by lodurr to Health & Fitness (17 answers total) 1 user marked this as a favorite
I don't know; I've been dilated most of my life for exams. I will add that I have nearsightedness and astigmatism and convergence insufficiency, and have had better eye exams since I started going to a Dr who was part of COVD.
posted by tilde at 7:06 AM on May 16, 2013

Are they doing the dilation before you do the vision test? That seems weird to me. I've only had my eyes dilated twice but both times it was the last thing we did after we'd already figured out my new prescription, done the peripheral vision test, and done the eye pressure test. Doing it before the vision test seems like it would be a terrible idea to me, I can't see a thing after that, I have no idea how I could accurately do a vision test with my eyes dilated.

But I will add that communication is key. Your prescription depends quite a bit on what you are using your eyes for. We decided not to up my prescription as much at my last appointment because it would start to interfere with my close up vision (I'm near-sighted) and since I work on a computer all day having close vision be blurry would have been a giant pain.
posted by magnetsphere at 7:19 AM on May 16, 2013 [2 favorites]

IANAOphthalmologist. That said, I don't think so. The reason your eyesight is worse as your pupils get dilated is that the spherical aberration of your eye increases dramatically with pupil size. This can usually be observed at night when you look at a bright light source—you'll see a halo, which is the result of the aberration induced by dark-dilated pupils. When your pupils are chemically dilated to ~7 mm diameter, the effective resolution is drastically lower than normal vision.

Now, whether or not this would screw up your ability to subjectively judge the prescription you's possible, I guess. But what glasses correct for is astigmatism and defocus, which operate independently, so you are still trying to reach the best vision—it's just that "best vision" will be blurrier than everyday vision when you're dilated.
posted by Maecenas at 7:22 AM on May 16, 2013 [1 favorite]

Response by poster: With this guy, it's always dilation before exam. In fact, I can't definitively remember it being any other way. I seem to vaguely recall that the ophthalmologist I saw as a kid waited until after the exam to dilate, but I can't be sure.

I tried to be very clear this time about what I needed: bifocals to replace my distance glasses, with distance correction on top and workstation screen correction on the bottom. What I've got is clear at around 3-4 feet on top, and 8-16 inches on the bottom. So they're not really useful for anything. And they cost me around $800, out of pocket.
posted by lodurr at 7:32 AM on May 16, 2013 [1 favorite]

Best answer: You need to switch doctors. Dilation isn't necessary every time unless you are at risk for certain things and it is generally done after the eye test. I haven't had my eyes dilated since I was a teen. A few years ago, I had a new test done, where a computer takes pictures of my eyes at all angles and then maps them on a screen for the doctor to review- way more accurate that dilation.
posted by myselfasme at 7:41 AM on May 16, 2013 [1 favorite]

Can you waive the dilation procedure? At my doctor's, you have the opportunity to waive it if you sign a form. Maybe try waiving it once to see if there is any difference with the outcome of the prescription.
posted by nikkorizz at 7:43 AM on May 16, 2013

Are you sure the place making your glasses isn't the one making mistakes? If you are sure the glasses match the prescription you were given, then I suggest the solution to your problem is a better eye doctor. The one you have is either not listening to you and what you say you need/want or is incompetent.
posted by Orb at 8:01 AM on May 16, 2013 [1 favorite]

Response by poster: i've been using this optician for about 12 years (with one stab at using another optician who's actually covered under our plan -- that was a disaster, they couldn't make glasses for me that didn't have wicked chromatic artifacts). They've given me a bad prescription on one other occasion, and it turned out the prescription was off. It's a local chain with a long history and a lot of good references other than me. I'm pretty confident in them. (Plus, they said they rejected one set of lenses on the order because they were wrong. So I know they're checking.)

this ophthalmologist, i've been using about 4.5 years -- 2 previous visits.

Re. waiving dilation: It hadn't occurred to me before that I could or should, but I'm sure I can, and of the 2 previous occasions I've had to be re-examined (once at another shop), they didn't dilate -- so when I get re-examined, there won't be dilation.

I think they do it first for workflow reasons: They have the tech to dilation & preliminary exam, then route me to the Ophth. I'm sure it's easier for them logistically.
posted by lodurr at 8:10 AM on May 16, 2013

Best answer: New doctor, stat. Even if the optician is screwing up, the doctor can and should check the actual glasses to make sure they match the prescription. If they don't, the glasses should go right back.

For whatever reason, the doctor is just plain ordering the wrong prescription for the glasses (or not catching mistakes by the optician--either way, it's the doctor's fault and not yours) and that is the doctor's fault, not yours.

Meanwhile, you shouldn't have to pay for glasses for which the doctor ordered the wrong prescription, regardless of the reason. I would complain firmly and threaten to and then actually do lodge a complaint with the state licensing board for your doctor if they don't fix the situation.

It sounds like, for various reasons, getting the right prescription for you is a bit of a challenge, but that means you need a competent doctor, maybe one who is a bit of a specialist in difficult cases, not someone who just makes mistakes and then foists the expense on you.

Also, if the glasses don't meet your requirements* I would most definitely refuse to accept them and also refuse to pay for them.

* And I mean in the way you describe, which is clearly and obviously far, far off from what you need and asked for. All new glasses are a bit annoying and 'off' at first, compared with your previous glasses. Or maybe you decide you don't really like the color you ordered. Those are your own mistakes and just buck up and pay for them.

But what you are describing above like, completely wrong, completely useless, it's not your fault that they are useless, and you should never have to pay for someone else's expensive mistake on something like this.

posted by flug at 9:03 AM on May 16, 2013 [1 favorite]

I have really bad astigmatism and really hard to make lens requirements (not bifocals - yet. My god I'm so screwed when that happens). I have to take my glasses back to the ophthalmologist to check after they make them it needs to be so precise and they have been sent back once.

It seems really strange to me that they are dilating you for the vision check (eye chart, "which is better this one or this other one that seems basically exactly the same"). In my case, I go in and do all of that stuff first, then my eyes are dilated and I'm sent to the waiting room for 15 minutes or so while the drops do their thing, then back in for the rest of it, then more sitting in the waiting room to let the drops wear off some. I think you need a different eye doc.
posted by marylynn at 9:07 AM on May 16, 2013 [1 favorite]

Response by poster: They do two series of vision tests. The tech does some, then the ophthalmologist appears to re-do the same tests, but spends more time on the astigmatism.

My drops take hours to wear off, FWIW. This last time I was examined late afternoon, and by bedtime I still couldn't see well enough to read without significant discomfort. I really shouldn't have driven home, and that was an hour after I was first dilated.
posted by lodurr at 9:13 AM on May 16, 2013

Sorry if I missed this in the thread, but what is the doctor looking for with the dialation?

If it's just examining the retina, that can be done without dialation if he has some newer equipment like the Optomap that can photograph the retina without any prep. I'd find a new doc with better equipment.
posted by JoeZydeco at 10:37 AM on May 16, 2013

Response by poster: They've got all kinds of equipment. They used a new-looking laser-guided camera on me. I think this may be just an issue of traditional behaviors.

Maybe I'll go back to Empire next time and insist on no dilation. At least that will be direct to insurance and I can just demand they give me the scrip to take to my opticians.

anyway, thanks everyone for your feedback. going in shortly for a re-exam; will come back and report later.
posted by lodurr at 11:31 AM on May 16, 2013

Best answer: Your optometrist could be a fierce dilator because some people are overcompensators and he can get a more accurate prescription when the eye muscles are somewhat paralyzed by the dilation. But he should really do the refraction both before and after just to be sure.

And do you make sure that your optician puts a "no tolerance" notation on your lenses order? I assume that they check the lenses against the script when they arrive. The acceptable level of variation allowed is surprisingly large, but there are some people who need to have it exactly as specified. For example, I can tell and can't use glasses when the axis is more than one degree off, though at my lens strength the acceptable variance is 5 to 7 degrees IIRC.

Four optometrists got very very tired of me not being able to get used to my glasses. The last one was so fed up that he told me that if I couldn't get used to the lens for my right eye, his best suggestion was to patch it and learn to live with one eye. Not joking. I like the one I've got now, but it is frustrating when they can't or won't listen or do anything for you. At least I have a very good and tolerant optician at a place with a great redo policy.
posted by monopas at 1:37 PM on May 16, 2013

I've always been leery of the dilate first always practice. Seems like a waste of effort and discomfort, unless there is some physical defect they are trying to compensate for. If I can see out of my eyes, they can see in. As my own eye doctor (and dentist) has gotten older, they just switch to using stronger tools to see what they need to see. Like the glasses mounted magnifier things, and the eye doctor's handheld magnifier/blinding light tool.

Glasses are damned expensive, and there is a LOT of profit in them. I would always insist on perfection, or at least an explanation of why perfection is not possible. (Like, for example, the last time I was talking lenses, the doctor explained that I can either have the fish-eye effect, or color aberration. More of one, less of the other. Choose my poison.)
posted by gjc at 4:20 PM on May 16, 2013

Response by poster: Here's at least part of the deal: when the prescription was written, they didn't take account of the difference between distance from my eye to the inside of the lens of my glasses, and the distance from my eye to the lens of the diagnostic device.

I spent something over an hour doing tests with a technician at the practice who concluded that I shouldn't have been given a change in prescription -- they couldn't find any evidence that actual glasses would provide an improvement on what I had. She reached this conclusion after documenting that the prescription I was given was accurate when dialed up on the machine, but also documented that my eyesight was better with my old glasses than it was with lenses mounted onto one of those diagnostic frames they use.

She has to get the findings blessed by the doc tomorrow. Still remains to be seen what will be done about the $1200 spent on new glasses and lenses.

Again, thanks for all your input. This is all good future information for the next go-round, which will be with a different doc & probably a different practice. (Though the tech I worked with today was very thorough, I just don't trust them now.)
posted by lodurr at 5:55 PM on May 16, 2013

Yes. Get a new optician.
posted by BenPens at 6:18 AM on May 17, 2013

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