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Thread: Mr. Bazan, OD ->does pupil dilation affect eye exams ?

  1. #1

    Question Dr. Bazan ->does pupil dilation affect eye exams ?

    My eyes are very strained and tense. In the eyes exam, I couldn't focus my eyes and things kept on popping up and then disappearing, which obviously made the eye exam impossible. My Clinical Optometrist says that it's reflected in the eye exam as a higher prescription than what I really need. She claims that by conducting eye-tests for prescription glasses after dilating the pupils and numbing (paralyising the eye muscles-I guess the focus muscles) she could reveal the "true" prescription. Her reasoning is that pupil dilation enlarges and relaxes the muscles that make the pupil constrict as well as relax the muscles that focus the lens of the eye, and makes it numb. She concludes, that the focus muscles are in a neutral state and doesn't affect the test results.

    What's your take on that ? and then I have a follow up if you don't mind.

    thank you very much in advance.
    Last edited by HOSADOS; 15-Jun-2008 at 16:59.

  2. #2
    A cycloplegic refraction is very common procedure. A cycloplegic eye drop is used to relax the focusing system and then your eye glass prescription is determined. In individuals that utilize their focusing system while looking in the distance, mostly hyperopic aka farsighted individuals, a cycloplegic refraction can be useful in prescribing a better pair of glasses. With the focusing system relaxed you get a more accurate idea of the eyes natural state.

    Example (simplified). A person is found to have an Rx of +1.00. However, this person always has eyestrain or difficulty focusing, especially while reading. A cycloplegic refraction is done and now the Rx is found to be +4.00. +3.00 diopters of farsightedness was revealed. That was the amount of focusing that was constantly being exerted while they were looking far away, and even more when looking up close. It was also the likely reason for their symptoms. Now a new Rx is issued based on this new information found from the cycloplegic refraction.

  3. #3
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    Some OD complaints: drops and exam rooms

    Hosados does not say whether the cycloplegic exam resulted in a stronger "plus" or "minus" prescription.

    While I agree that dilation is useful to reveal hyperopia, I don't think it's appropriate to use for myopes---medium to high myopes. It may result in a higher minus prescription. I always refuse the dilation when I go in for a refraction. Seems like the usual routine for a refractive exam always includes the dilation---but this is so they can do an inspection of the retina and maybe pick up on any obvious problems---all while they have you in the office.

    And again, the glaucoma pressure test is part of the routine. They instill 2 types of numbing drops. All of these drops cause my own dry eyes to go into distress, and make it very hard to see---to get an accurate prescription.

    Adding to that is the sad fact that most optometrists' offices have installed the reflecting mirror system eye chart---which allows them to make the exam rooms smaller. They can get more exam rooms per square foot into their office. Problem is---that projected and reflected image is harder to see, and this results in a faulty prescription.

    I notice too, that the projected image isn't necessarily "straight"--it isn't horizontal--and they don't fix it unless you ask. And who knows enough and is brave enough to ask the doctor is adjust it? This really messes me up, because I have oblique astigmatism and it interferes with the axis measurement. You would think optometrists would take these factors seriously, but they usually don't. And I would like some acknowledgment that there is considerable variation between the exam rooms from office to office---different light levels, quality of projected image, etc. All this contributes to slight errors, and while it's true that we usually "get used to" our prescriptions, even if they're not accurate, why shouldn't we strive to eliminate some of the variables and get an Rx closer to the "real thing?"

    Just give me an old-fashioned 20 ft exam room with an illuminated printed chart---something crisp to begin with. And no eye drops or dilation before the exam, please.

    Call me old-fashioned.

    Calli

  4. #4
    Quote Originally Posted by calli66 View Post
    While I agree that dilation is useful to reveal hyperopia, I don't think it's appropriate to use for myopes---medium to high myopes. It may result in a higher minus prescription.
    Hi Calli, Thanks for participating. Can you explain how a higher minus prescription might result for medium to high myopes?

  5. #5
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    We myopes don't see well at a distance when our pupils are dilated! Anecdotal evidence, I suppose, based on me, my family, my myopic friends and acquaintances. Call it the "depth of field" effect---the fact is, myopes have sharper vision when our pupils are doing their "normal" thing. That is---not wide open with light scattering everywhere. And how does dilation with the goal of discovering latent hyperopia apply to those of us with presbyopia? There has to be a CLEAR reason to dilate---not just "oh, it's part of the exam."

    Because we aren't seeing the chart as well as we normally would, the doctor will try to help by increasing the minus power on the phoroptor. This extra power in the Rx is not needed when the pupils are at their normal size. Moreover, when we're outside in bright light, our pupils constrict even more, giving us sharper vision still.

    I think it's especially important for those of us with dry eyes---when we go in for a refraction exam---that we do the glaucoma and dilation exams separately--or at least after the acuity exam. Our vision is pretty variable to begin with due to corneal irregularities, swelling, incomplete tear layer, etc. If the goal is to get the most accurate exam possible---which I think is a good idea---then both doctor and patient have to minimize the variables. This is not just idle wishing---glasses can be very expensive, and it would be good to get it "close to" right the first time.

    Dr Bazan---what do you think about any of this? I know I'm on a bit of a rant, and I don't mean to offend you or to say all optometrists are insensitive. I'm just not sure they understand what it's like to be very myopic, with eye pain and eye fatigue, feeling blind and insecure, etc.---stressed and trying to see some tiny fuzzy line of letters in a dark room.

    It feels like the exam is set up so that we're being tested under conditions where our vision is at its very worst. As for me, I do not need an everyday pair of glasses that corrects me to 20/20 when worn while driving at night in a thunderstorm. I have a stronger pair for that, and keep them in the car.

    Calli

  6. #6

    Unhappy

    Many thanks Dr. Bazan.
    First of all I should say I'm hyperopic aka farsighted. If I'm not mistaken my current glasses prescription is L: -4.5 or 4.75 R: -4.75 or 5 (don't remember will check it out, also don't remember the Cyl numbers). about two months ago I took and eye exam and here are the resutls:

    L: sph -4.25 cyl -1.25
    R: sph -4.5 cyl -0.75

    Early, this week I took another eye exam with a developmental optometrist and here are the result:
    RE -4.50 / 1.25 x 10
    LE -4.25 / -1.75 x 2

    Having said that, while I don't have this in front of me about three weeks ago
    I took an eye exam with a clinical optomterist and that was the incident I described in my previous post. After probably using A cycloplegic, the
    prescription she came out with was 1.5 lower than the my current glasses number (probably around L: -3 R: -3.25.

    You would agree this is a huge gap. To be honest the whole thing is very confusing. I feel that my DES and make my eyes strain, which I always knew and argue it distort the evaluation. Hence, this gap make sence to me.

    Having said that, who is to say, that even with A cycloplegic this the correct number ? Even under the influence of A cycloplegic, I still felt a lot of strain and pressure, and felt that when my eyes are more relax and comfortable my vision would be still much better.

    All this bring me to ask you two important parctical questions:

    (1) In theory, if take another eye exam with A cycloplegic, but this time I come to the exam with my eyes relax with no or very little strain. Would it be possible for the prescription number resulted from this exam to be somewhat different from the previous eye exam I took under the influence of A cycloplegic ?

    * I geuss it's a really a question of whether A cycloplegic completely relax /numb the muscles or not. I feel it's not relax the muscles to their full exten, and therefore I should take another eye exam under A cycloplegic, this time coming when my eyes are more relax and comfortable. I should say the Clinical Optometrist, claimed it completely relax and numb the muscles, which contradict my personal experience

    (2) The Clinical Optometrist argued, that I should have new glasses made with the 1.5 lower prescription number, and in order to adjust my eyes to that, I should take visual therapy and excercises for the eyes. She didn't deny that fact that until my eyes would get adjust to this lower number, I won't be able to see well, and this could take months !!!

    I told this to the Ophthalmologist I last saw, and he said I should probably have a 1 or 0.5 lower number since, under normal condition my eyes are strained and therefore 1.5 lower number would be to low, and I won't be able to see well. Having said that, he didn't want to get involved with this and said this the job of the Optometrist to determined my glasses prescription.

    I really don't know what to do ....I should mention I need to have at least the new glasses (1 for computer use, 1 PantOpx wraparound, 1 normal glasses and maybe one more) so this would have a huge impact on my cost and first and for most on my HEALTH.

  7. #7
    Quote Originally Posted by calli66 View Post
    We myopes don't see well at a distance when our pupils are dilated! Anecdotal evidence, I suppose, based on me, my family, my myopic friends and acquaintances. Call it the "depth of field" effect---the fact is, myopes have sharper vision when our pupils are doing their "normal" thing. That is---not wide open with light scattering everywhere. And how does dilation with the goal of discovering latent hyperopia apply to those of us with presbyopia? There has to be a CLEAR reason to dilate---not just "oh, it's part of the exam."
    Hi Calli66, you makes some great points about depth of focus and overminusing because of a lack of percived clarigty. Dilation and cyclopegia are related but not the same. I agree there should be a reson for everything that is done, and there are many reasons to preform cycloplegic refractions. In myopes, it is most commonly done when the focusing system is unstable, overactive or unresponsive. Most of the time if a myope is being cyclo'd its at a lasik consultation or by an optometrist who has a good working knowledge of accommodative and binocular disorders. It is definetly an uncommon thing for a "normal" myope to have this procedure done.

    Quote Originally Posted by calli66 View Post
    Because we aren't seeing the chart as well as we normally would, the doctor will try to help by increasing the minus power on the phoroptor. This extra power in the Rx is not needed when the pupils are at their normal size. Moreover, when we're outside in bright light, our pupils constrict even more, giving us sharper vision still.
    An easy but often forgotten technique to check for overminusing is called a +50 check. If adding +50 does little to the sharpness, and only makes the black look a lighter color, you can conclude you added to much minus.

    Quote Originally Posted by calli66 View Post
    I think it's especially important for those of us with dry eyes---when we go in for a refraction exam---that we do the glaucoma and dilation exams separately--or at least after the acuity exam. Our vision is pretty variable to begin with due to corneal irregularities, swelling, incomplete tear layer, etc. If the goal is to get the most accurate exam possible---which I think is a good idea---then both doctor and patient have to minimize the variables. This is not just idle wishing---glasses can be very expensive, and it would be good to get it "close to" right the first time.
    All true. The variability in the visual acuity because of the many factors makes it very hard to get a stable Rx. An Rx will always be "as good as we can get it" if there is an instability of the refractive state of the eye. Dr. Latkany uses a TNT test which dramatically demonstrates this. I think an eye doc may come off as insensitive to a patient he fails to manage their expectations. I try to always set realistic expectations to avoid having patients with goals that no one can achieve. For example, you may hear me say, " I am very please we were able to get a great prescription for you today. As you know the quality of your vision can vary dramatically because of x,y,z. These glasses wont resolve those issues, but take comfort in knowing that we have found the best prescription for maximizing and maintaining clear vision." It is important to understand that vision fluctuates, especially with dry eye patients, and that typical glasses don't treat ocular disease.


    Quote Originally Posted by calli66 View Post
    It feels like the exam is set up so that we're being tested under conditions where our vision is at its very worst. As for me, I do not need an everyday pair of glasses that corrects me to 20/20 when worn while driving at night in a thunderstorm. I have a stronger pair for that, and keep them in the car.
    Make sure you doc knows this. I prescribe multiple pairs to resolve multiple issues all the time. It is important to communicate your needs in order for them to be met in the best possible way.

  8. #8
    (1) In theory, if take another eye exam with A cycloplegic, but this time I come to the exam with my eyes relax with no or very little strain. Would it be possible for the prescription number resulted from this exam to be somewhat different from the previous eye exam I took under the influence of A cycloplegic ?

    * I geuss it's a really a question of whether A cycloplegic completely relax /numb the muscles or not. I feel it's not relax the muscles to their full exten, and therefore I should take another eye exam under A cycloplegic, this time coming when my eyes are more relax and comfortable. I should say the Clinical Optometrist, claimed it completely relax and numb the muscles, which contradict my personal experience


    The drops are time dependent. There could be some fluctuation as a result of how much time had passed from installation of them to your exam. This also varies with the individual. Impractical to adjust for this. I would not worry about the small amount of variation at all. However, if it would make you feel better, I would have it redone. Verifying results is never a bad thing. Also, if your farsighted, hyperopic, all of those (-)minuses should be +. Is it + or - ?

    (2) The Clinical Optometrist argued, that I should have new glasses made with the 1.5 lower prescription number, and in order to adjust my eyes to that, I should take visual therapy and excercises for the eyes. She didn't deny that fact that until my eyes would get adjust to this lower number, I won't be able to see well, and this could take months !!!

    I told this to the Ophthalmologist I last saw, and he said I should probably have a 1 or 0.5 lower number since, under normal condition my eyes are strained and therefore 1.5 lower number would be to low, and I won't be able to see well. Having said that, he didn't want to get involved with this and said this the job of the Optometrist to determined my glasses prescription.


    There are other ways to provide relief to a straining focusing system. Was the idea of multifocal's discussed? VT is capable of some pretty incredible things. There are a ton of success stories, and some very ecstatic people. I would encourage you to learn more about it and ask what you can expect out of it. Also, when you hear something like it can take months to adapt, also realize that it is possible that it could only take a few days to adapt. Did you try out the new Rx in the office for any period of time? I utilize a piece of equipment called a trial frame a lot which gives you a preview of your glasses.

  9. #9
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    Thanks, Dr. Bazan----for clarifying that there's a difference between dilation and cycloplegic eye exams. I actually didn't know that. And I'm not sure if or when my eye doctors have used the cycloplegia.

    I looked at your web-site---it really seems like you are an exceptionally caring doctor, and thanks doubly--for taking the time to be part of Dry Eye Talk.

    I have only recently (in the last year), felt relaxed enough during eye exams, to really communicate my vision requirements to the eye doctor. The other thing I'm getting better at doing is figuring out how to "see" the eye chart lines in such a way as to get the best correction for my weird astigmatism axis. I have had so many "loser" pairs of glasses because of this problem.

    Sometimes I think there should be "training" for the patient---in what to look for, more specifically. Like maybe examples of what "clear" is supposed to look like. For me, it's the "ghost image" issue---the "drop shadow" behind an otherwise fairly clear letter. Without the axis correction at the right angle, 20/20 has a clear appearance, but I just can't read it.

    This has caused some difficulty in communication, especially with the techs in the ophthalmologist's office. When I can't read a line on the eye chart, they increase the minus, but I still can't read it. Then they tell the doctor that my "vision can't be corrected to 20/20." Of course, this sets off alarm bells. Several years ago they set me up for a fluorescein angiography to see if I had macular degeneration. But I just KNEW I could be corrected to 20/20---and got a special hour-long appointment with my optometrist to confirm it----which she did.

    Sorry to go on about this. I just never would have thought getting an accurate refraction would be so difficult. For some of us, it is. We don't want to be "difficult patients," but that's the way it is.

    Calli

  10. #10
    Hi Calli. You're welcome and I enjoy the time I spend here.

    I want you to become more comfortable with what is involved with all of the factors that goes into how you see with a pair of glasses. The goal of my refraction is to help the pt get their visual acuity as good as it can be and help get them comfortable with that level of acuity.

    20/20 doesn't resonate a concrete level of vision to me. Even if my 20/20 line is physically identical to others, there are many variables which may make it "different". There are variables in the ambient conditions, the equipment, the setup, your eyes, and your perceptions. Don't forget you have to take that Rx and make a pair of glasses which has a whole new set of variables and then use it in a world void of 20/20 lines.

    That means that the hour long refraction you did, might yield a fantastic pair of glasses, but they may not be fantastic all of the time or forever. They might not even be as good as you can get! The point is, is that you feel that they are....analyze what it took to get you to feel that way. Then you can help out next time around. What did you need in terms of care, instructions, education, setup....etc. If you can minimize the variables, you will maximize your success.

    Your doctor did a great job recognizing that in order to get your perception of a great prescription, it would take a special hour long appointment. Keep in mind most refractions take far less time. If the subjective refraction is taking longer that 5 - 10 minutes, its because the doctor is helping to make the patient feel comfortable about the Rx and/or there is some inherent variable that is preventing a stable Rx from being determined that either needs to be resolved or accepted.

    One of the techniques that I utilize to help accomplish this is a self refraction. I will literally say, "ok, there is a lot of variability in your vision. Since nobody but you knows exactly how you like to see things, I am going to let you customize your own prescription." I usually let them only refine the cyl (turning the dial on a manual phoroptor). It does a couple of things. 1 it gives people the opportunity to see that things are as good as both myself and them can get them. 2. it shares the responsibility of the Rx. I find it works very well for indecisive people. With indecisive people, I may mention "just get it as good as you can, I will double check you". The last step is to put that Rx into a trial frame, to give them a preview of what to expect. I do all of this to ensure you are comfortable with the Rx and that you think it is the best Rx for you. In actuality, it may be different that what I would have normally prescribed! But I think you get my point.

  11. #11
    bad thing. Also, if your farsighted, hyperopic, all of those (-)minuses should be +. Is it + or
    it's - and my problem is distance vision

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