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Medical Forum / General / Vision / February 2005how commonly do optometrists miss glaucoma?
Four months ago I complained to my optometrist that my peripheral vision was blurred. I asked if it could be glaucoma. My pressures were 17 and 18. I asked about normal tension glaucoma. She explained that they look at three things to diaganose glaucoma: the pressures, the optic nerve, and the visual field. I did a visual field test three times but it was so inconsistent (even with my good eye) she said she could not explain it. She did a dilated eye exam and told me my optic nerves looked healthy but "large." She went through my records for the past several years and noted there had been no change in the optic nerve. I have high myopia so she explained that "large nerves"--I guess she meant large cups--were typical with myopes. She said to show my visual field tests to my retina specialist, which I did. He said the test was so inconsistent it was meaningless and not to worry about it--something about that kind of test not being sensitive enough for high myopes. Now my blurry peripheral vision has advanced considerably and I am expecting, as my doctor now says is likely, a diagnosis of very advanced glaucoma. My retina specialist, who also didn't notice any optic nerve damage but finally had me do another visual field test, says that sometimes optic nerve damage is subtle and easily missed. Does that sound likely? If so, how do normal tension glaucoma patients ever get diagnosed before it's almost too late? I have so much vision loss now I think it's almost too late for that eye. Then you can only resort to the only thing that works: rest treatments. Discard your glasses and start the self-treatment under the supervision of a person gifted with perfect sight: read the book by Dr. Bates. It is a good book and explains very well why you have choosen the wrong path of strain and effort to see. It is 100% safe. <duck> QUACK QUACK QUACK QUACK </duck> > <duck> QUACK QUACK QUACK QUACK </duck> Idiots do exist. I missed this one. >><duck> QUACK QUACK QUACK QUACK </duck> > > Idiots do exist. > I missed this one. Awww. And I thought he captured your essence so perfectly. Never mind. you can't win them all, eh Rishi my old friend? > Awww. And I thought he captured your essence so perfectly. > > Never mind. you can't win them all, eh Rishi my old friend? I missed you too. In some ways glaucoma can be one of the most difficult things to test for... there is no single "glaucoma test" that gives you a straight yes or no diagnosis. Glaucoma is diagnosed by doing a number of tests (including pressures, visual fields, and optic nerve evaluation, and others too), then looking at the patient's age, family history, and forming an overall opinion. Sometimes the information gathered makes it easy to say "yes you've got it", but often the information is not conclusive and it's a bit of a judgement call. Optic nerve apperance varies between individuals, and some people are born with a healthy optic nerve that has the appearance of a glaucomatous one. Therefore a suspicious looking nerve is an indicator of possible glaucoma, but certainly not definitive proof. Even the same test repeated over time can give different results - eg. pressures can vary from day to day, and within the day; and visual field tests can fluctuate from one test to the next - only a consistent defect repeated over time is conclusive. Often concentration or tiredness can create an inconsistent visual field result, so a suspcious visual field is usually just repeated at some future date for verification. Normal-tension glaucoma is even harder to diagnose, as one of the main indicators of glaucoma (raised intra-ocular pressure) is not present. And the decision to diagnose glaucoma, and therefore put someone on daily eyedrops for the rest of their life, is not taken likely. So the diagnosis is not made on the basis of just one or two suspicious findings, but a more complete pattern or some more definititive test results. Having said all of this, if your glaucoma is advanced enough that you can notice blurry peripheral vision yourself, then this should have been very, very obvious on the visual field test. Usually computerised field tests pick up defects years earlier than they are actually noticed by the person. Hope this helps Dom "gudrun17" <yngver@aol.com> wrote in message news:1107554966.657858.98880@l4 1g2000cwc.googlegroups.com... > Four months ago I complained to my optometrist that my peripheral > vision was blurred. I asked if it could be glaucoma. My pressures were [quoted text clipped - 20 lines] > ever get diagnosed before it's almost too late? I have so much vision > loss now I think it's almost too late for that eye. Dom's reply was very well stated. I'd like to add a few things and draw your attention to a couple of key points: > the decision to diagnose glaucoma, and therefore put someone on daily > eyedrops for the rest of their life, is not taken likely. So the diagnosis > is not made on the basis of just one or two suspicious findings, but a more > complete pattern or some more definititive test results. This is very important, as once a patient is started on glaucoma medication or surgical intervention, it is often impossible to after-the-fact re-evaluate the original diagnosis. > Having said all of this, if your glaucoma is advanced enough that you can > notice blurry peripheral vision yourself, then this should have been very, > very obvious on the visual field test. Usually computerised field tests pick > up defects years earlier than they are actually noticed by the person. Agreed. Additionally, there is now technology that can quantify the degree of nerve fiber loss and monitor to progress of the disease, or better, the efficacy of the treatment. Sometime pressure in the upper range of normal is really higher than measured. This, too, is now avoidable with current technology. Nevertheless, normal-tension glaucoma and even elevated pressure glaucoma is not a simple diagnosis. So, to answer your subject of your post, I think in 2005, it would be very unusual for us to miss glaucomatous nerve damage. Not impossible, but not very likely. We DO, on the other hand, as Dom wrote, like to be pretty darn certain that the condition exists before beginning treatment. That does not mean we "miss" detecting it, but it does sometimes mean a delay in reaching a definitive diagnosis. (The "we" referring to competent optometrists, general ophthalmologists and retina specialists.) You might want to ask about retina nerve fiber imaging and if that is likewise inconclusive, having been to a retina specialist, I would think the next referral would be to a neurologist. Do let us know what happens. --LB, O.D. > Dom's reply was very well stated. I'd like to add a few things and draw > > Having said all of this, if your glaucoma is advanced enough that you can > > notice blurry peripheral vision yourself, then this should have been very, > > very obvious on the visual field test. Usually computerised field tests pick > > up defects years earlier than they are actually noticed by the person. The visual field test done by the optometrist showed gross inconsistencies over three separate tests--in other words, an area that showed came up black (this was the Humphrey frequency doubling test) showed up white (normal) in the next text but there would be a different defect (grey or black) in a different part of the eye that before tested normal. There were more defects in the affected eye but in one test but not in the other two, which showed more defects in my good eye. The OD said she could not explain it, as I said, and told me to show them to my retina specialist. He said they were too inconsistent to mean anything. Actually he said I should wait until my PVD "resolved" to have vision field testing, because I even asked about having one done there. It wasn't actually until I showed him results of an online visual field test that he decided I better have one done in the office, and that's the one that showed "suspicion of glaucoma." > Agreed. Additionally, there is now technology that can quantify the > degree of nerve fiber loss and monitor to progress of the disease, or > better, the efficacy of the treatment. Sometime pressure in the upper > range of normal is really higher than measured. This, too, is now > avoidable with current technology. Nevertheless, normal-tension > glaucoma and even elevated pressure glaucoma is not a simple diagnosis. > > So, to answer your subject of your post, I think in 2005, it would be > very unusual for us to miss glaucomatous nerve damage. Not impossible, > but not very likely. Okay, that's the part I'm wondering. I understand that with normal pressures and with myopia, sometimes it can be harder to catch, but over the past five months I've seen the OD, an ophtalmalogist, and my retina specialist (who brought in a colleague to examine me as well) and it's difficult for me to understand how they could all have missed this. Meanwhile the blurry area kept extending closer to my central vision, scaring me, but still my retina specialist said he could not detect any optic nerve damage. I have seen him about five times during this time period, and I asked him if he saw any changes in my optic nerve, and he said no. He also said he had not thought it could be glaucoma because I was complaining of rapid progression, and supposedly glaucoma is slow. We DO, on the other hand, as Dom wrote, like to be > pretty darn certain that the condition exists before beginning > treatment. That does not mean we "miss" detecting it, but it does > sometimes mean a delay in reaching a definitive diagnosis. (The "we" > referring to competent optometrists, general ophthalmologists and retina > specialists.) Thank you. But it seems to me that if a patient is asking if it could be glaucoma and complaining of loss of vision, surely the OD or the ophtalmalogist or the retina specialist would, although hesitating to make an actual diagnosis, consider the possibility? Or would they normally take a look a the optic nerve, decide they see no damage and take a wait and see approach? Everyone told me they didn't see anything suspicious. Of course, I understand that retina specialists are concentrating more on retinal tears--which is what they first thought my symptoms indicated, but that was ruled out. > You might want to ask about retina nerve fiber imaging and if that is > likewise inconclusive, having been to a retina specialist, I would think > the next referral would be to a neurologist. > > Do let us know what happens. > > --LB, O.D. Thanks for the suggestions. I'll see what the glaucoma specialist says. I was just trying to understand how a group of eye care specialists could be telling me my optic nerves look normal when I obviously have advanced visual field loss. At this point most of my upper visual field is blurred and dimmer, which is a big change from a few months ago when I could only see the blurring in the far periphery. I am sure I will be having an MRI. I will post back. The retina specialist said maybe it's not glaucoma, but based on the field test he thought it likely is although he could not explain why he had noticed no damage. Obviously I am confused and distressed that this could not have been caught sooner before I lost more vision--like I said, a couple months have made a noticeable difference. As I read your latest post, one thing is clear: the whole picture is not here. You keep adding more information (like the the fields test being FDT, but not whether it was screening or threshold) and that you have PVD and other little bits and pieces. It is not possible for anyone here to give you a proper diagnosis or prognosis and my only reason for commenting was to address the subject of your post. Key points here are that you claim to have significant and rapid changes in visual field loss---something that is hardly possible with normal tension glaucoma. Glaucoma is known to be a slowly progressive condition with the notable exception of extremely high rapid onset pressure. > The visual field test done by the optometrist showed gross > inconsistencies over three separate tests--in other words, an area that > showed came up black (this was the Humphrey frequency doubling test) The FDT has a number of testing modes. There are other methods of measuring fields. Some people perform better with one or the other and certainly, one would think that if there were poor results with one technology that you would be tested with another. > Actually he said I should wait until my > PVD "resolved" to have vision field testing, because I even asked about > having one done there. It wasn't actually until I showed him results of > an online visual field test that he decided I better have one done in > the office, and that's the one that showed "suspicion of glaucoma." On-line test? Forget it. I should think that a $10K or $20K machine in an office would be a bit more reliable. > Meanwhile the blurry area kept extending closer to my central > vision, scaring me, but still my retina specialist said he could not [quoted text clipped - 3 lines] > glaucoma because I was complaining of rapid progression, and supposedly > glaucoma is slow. As I said. And as I started, we don't have all the data presented here and there is nothing anyone "on-line" can do for you, except to encourage you to get another opinion from a retina ophthalmologist and proceed rapidly with other neurological testing including imaging studies---both of the retina and brain. I wish you well. Do let us know the outcome of your follow-ups. --LB, O.D. > As I read your latest post, one thing is clear: the whole picture is not > here. You keep adding more information (like the the fields test being > FDT, but not whether it was screening or threshold) and that you have > PVD and other little bits and pieces. It is not possible for anyone > here to give you a proper diagnosis or prognosis and my only reason for > commenting was to address the subject of your post. Thank you for your info. I understand; I'm not really looking for diagnosis--, just trying to understand how reasonable it would be for eye care professionals to detect advanced glaucoma-induced changes in the optic nerve. The FDT test was for screeing, I'm sure. The optometrist had only gotten it a few months earlier--they never had offered visual field tests before. I'm not sure what difference the PVD would make, except that that's what my RS thought was causing the loss of vision at first. > Key points here are that you claim to have significant and rapid changes > in visual field loss---something that is hardly possible with normal > tension glaucoma. Glaucoma is known to be a slowly progressive condition > with the notable exception of extremely high rapid onset pressure. Thank you, that's info that's important for me to know. I don't know how slow is slow--whether there would be a noticeable loss over the course of a few months (noticeable to the patient, I mean) or whether it would normally take years. > > The visual field test done by the optometrist showed gross > > inconsistencies over three separate tests--in other words, an area that [quoted text clipped - 4 lines] > certainly, one would think that if there were poor results with one > technology that you would be tested with another. I suspect since the FDT was a recent acquisition, the optometry technicians may not have been well trained yet. I know they did not try any other modes of testing, other than to have me do one with my glasses and one with my contact lenses to see if it made a difference. > > Actually he said I should wait until my > > PVD "resolved" to have vision field testing, because I even asked about [quoted text clipped - 4 lines] > On-line test? Forget it. I should think that a $10K or $20K machine in > an office would be a bit more reliable. Yes, of course, but if only I'd showed him the print-outs of the online test a few months earlier, to document that I was missing more points in the field, I think he would have taken the situation more seriously and done a proper visual field test then, probably saving some of my vision. The test showed defects within 20 degrees of fixation, which is apparently what convinced him to order an office visual field test. I didn't think he would take an online test seriously either, which is why I didn't show it to him earlier. Now I obviously feel great remorse that I didn't document my visual loss sooner rather than just try to describe it to him and the other doctors I saw. > > Meanwhile the blurry area kept extending closer to my central > > vision, scaring me, but still my retina specialist said he could not [quoted text clipped - 11 lines] > other neurological testing including imaging studies---both of the > retina and brain. Thank you. I am just trying to gather all the information I can, since obviously I am baffled and scared. I have already scheduled a second opinion appointment with another glaucoma specialist for later this week. He seems to be willing to move a lot more quickly than my current ophthalmalogists. > I wish you well. Do let us know the outcome of your follow-ups. > > --LB, O.D. Thank you, you've been very helpful. I look for information and opinions online but I know very well that I must trust my doctors to diagnose. Getting opinions online, however, helps me get a better understanding of the situation so I can ask better questions of my doctors. I wish I had delved into this a lot more a few months ago, rather than just assuming my doctor's "wait and see--I think it will resolve on its own" advice must be accurate, because I might have been able to save more vision. > In some ways glaucoma can be one of the most difficult things to test for... > there is no single "glaucoma test" that gives you a straight yes or no [quoted text clipped - 9 lines] > Therefore a suspicious looking nerve is an indicator of possible glaucoma, > but certainly not definitive proof. So are you saying that if a person has optic nerve appearance typical of myopia, but complains of blurred peripheral vision, the OD could not tell by looking at the optic nerve whether there was any damage? As I noted, she did look back through my records (I am vigilant about having yearly exams) and said there had not been any change in my optic nerves over the past few years. Even the same test repeated over time > can give different results - eg. pressures can vary from day to day, and > within the day; and visual field tests can fluctuate from one test to the > next - only a consistent defect repeated over time is conclusive. Often > concentration or tiredness can create an inconsistent visual field result, > so a suspcious visual field is usually just repeated at some future date for > verification. I understand, and that's what happened, but the fields were so inconsistent from test to test she said she could not explain it. She said the fields looked typical of someone with dense cataracts, which I clearly don't have. > Normal-tension glaucoma is even harder to diagnose, as one of the main > indicators of glaucoma (raised intra-ocular pressure) is not present. And > the decision to diagnose glaucoma, and therefore put someone on daily > eyedrops for the rest of their life, is not taken likely. So the diagnosis > is not made on the basis of just one or two suspicious findings, but a more > complete pattern or some more definititive test results. But I think you are talking about early glaucoma detection. It seems to me that once a person is complaining of vision loss, starting treatment to stop progression would be more important than waiting to be sure. > Having said all of this, if your glaucoma is advanced enough that you can > notice blurry peripheral vision yourself, then this should have been very, > very obvious on the visual field test. Usually computerised field tests pick > up defects years earlier than they are actually noticed by the person. Is it likely that frequency doubling visual field tests are inaccurate with high myopes? That's what I was told, since there were such wild inconsistencies among the tests. >>In some ways glaucoma can be one of the most difficult things to test > [quoted text clipped - 43 lines] > yearly exams) and said there had not been any change in my optic nerves > over the past few years. A "myopic" optic nerve isn't quite the same thing as a "glaucomatous" optic nerve. But to answer your question, it is not always possible to tell a nerve is damaged just by looking at it - myopic or otherwise. The fact that your optic nerves had not changed suggests (but certainly doesn't prove) that there is no glaucoma. > Even the same test repeated over time > [quoted text clipped - 24 lines] > said the fields looked typical of someone with dense cataracts, which I > clearly don't have. Glaucomatous visual fields have a distinctive pattern to them, which is usually fairly easily recognised if it's advanced enough. If your fields resembled those of someone with cataracts, then that's a different pattern, and so no wonder your optometrist didn't immediately suspect glaucoma. If you don't have cataracts, and your visual fields don't resemble glaucoma, then you start to wonder what else may be causing your peripheral blur... especially given its fairly rapid progression. >>Normal-tension glaucoma is even harder to diagnose, as one of the > [quoted text clipped - 18 lines] > me that once a person is complaining of vision loss, starting treatment > to stop progression would be more important than waiting to be sure. Yes that's right -- *but* you have to be sure (1) the vision loss is present and measureable, and (2) it is caused by glaucoma and not something else, before you initate glaucoma treatment. Glaucoma is not the only cause of peripheral vision loss. If they jumped in and started you on glaucoma treatment earlier, but then your peripheral vision continued to deteriorate because in fact it was caused by a brain tumour and not glaucoma, then you'd be more than a little upset! Have you actually formally been diagnosed with glaucoma, or was this just one possiblity that has been suggested to you (or, have you done a self-diagnosis over the internet)? Because your story is not totally consistent for normal-tensive glaucoma. I don't mean to accuse you of anything, I just wonder whether you have jumped to this conclusion yourself when in fact there may be another cause. >>Having said all of this, if your glaucoma is advanced enough that you > [quoted text clipped - 15 lines] > with high myopes? That's what I was told, since there were such wild > inconsistencies among the tests. I'm no expert on FDT, but I think it's more accurate for high myopes and hyperopes than traditional visual field testing. Anyway, if you wear your contacts for the test it becomes irrelevant. I agree with LarryDoc that everything doesn't quite "add up" here and neurological testing might be a good idea. And beware of internet diagnoses! Dom > >>In some ways glaucoma can be one of the most difficult things to test > > [quoted text clipped - 45 lines] > > A "myopic" optic nerve isn't quite the same thing as a "glaucomatous" > optic nerve. But to answer your question, it is not always possible to > tell a nerve is damaged just by looking at it - myopic or otherwise. The [quoted text clipped - 34 lines] > resembled those of someone with cataracts, then that's a different > pattern, and so no wonder your optometrist didn't immediately suspect > glaucoma. If you don't have cataracts, and your visual fields don't > resemble glaucoma, then you start to wonder what else may be causing [quoted text clipped - 35 lines] > self-diagnosis over the internet)? Because your story is not totally > consistent for normal-tensive glaucoma. I don't mean to accuse you of > anything, I just wonder whether you have jumped to this conclusion > yourself when in fact there may be another cause. [quoted text clipped - 24 lines] > > I agree with LarryDoc that everything doesn't quite "add up" here and > neurological testing might be a good idea. And beware of internet diagnoses! > > Dom An absolute glaucomatous scotoma would not be preceived as "blur." It would not be perceived at all, because it would be a complete lack of vision. Something is rotten in Denmark. DrG > An absolute glaucomatous scotoma would not be preceived as "blur." It > would not be perceived at all, because it would be a complete lack of > vision. > > Something is rotten in Denmark. Aren't relative scotomas perceived as blur, or lack of resolution? One person I asked described it as a fuzzy spot. You know, one reason I believed my doctor that my increasingly blurred upper vision must be from a collapsed vitreous and could not be glaucoma is that the people I asked that I personally know who had vision loss from glaucoma described the loss as a complete lack of vision, as you say, a blind spot. I figured I could not have glaucoma since I am not totally blind even in the densest part of my visual loss--I can still perceive bright light in that spot, it's just blurred and diffuse. The rest of my visual field loss is gradually less and less blurry down to my central vision, which is still okay, although barely. It is my understanding now that vision loss from glaucoma often begins as areas of decreased resolution, as in a relative scotoma, and then these areas gradually become absolute scotoma. Am I mistaken? > An absolute glaucomatous scotoma would not be preceived as "blur." It > would not be perceived at all, because it would be a complete lack of > vision. > > Something is rotten in Denmark. I'd say! Each time he posts there's a little more information. It is difficult for me to understand how three competent practitioners in a row could not come to a diagnosis or at least a protocol for finalizing a diagnosis and then treatment plan. There's simply a limited number of potential causes and a limited number of diagnostic tools to get there. Comments on other posts: I have no problem not completely trusting a doctor's judgment and pursuing alternative opinions. Nor do I have a problem with "doing your homework" and presenting a doctor with specific questions to be addressed. If the practitioner fails to ask for information you think might help in the diagnosis, feel free to add it! I've has occasion when I diagnosis something and at the conclusion of the visit, he/she adds a "by the way, it also happens when.......". And that little clue throws out the first diagnosis. Re: FDT. I don't think it correct to state that it is a superior field testing device. Like all computer-assisted field testing devices, it has its strengths and weaknesses. If one machine fails to provide reliable data, we use another. Even if it does provide excellent quality data, it's not unusual to re-test on a different machine with a different protocol. (I use one all the time, every day.) LB, O,D. > > An absolute glaucomatous scotoma would not be preceived as "blur." It > > would not be perceived at all, because it would be a complete lack of [quoted text clipped - 3 lines] > > I'd say! Each time he posts there's a little more information. You're right. I tried to simplify it in the first post--I couldn't very well get every detail in one post. It is > difficult for me to understand how three competent practitioners in a > row could not come to a diagnosis or at least a protocol for finalizing > a diagnosis and then treatment plan. There's simply a limited number of > potential causes and a limited number of diagnostic tools to get there. That's what I'm trying to understand too. The O.D. basically handed me off to the retina specialist. My retina specialist is just now handing me off to the glaucoma specialist. I don't know why he didn't think it was worth testing my visual fields before now. He seemed to be thinking all along that it was a vitreous problem. > Comments on other posts: > > I have no problem not completely trusting a doctor's judgment and > pursuing alternative opinions. Nor do I have a problem with "doing your > homework" and presenting a doctor with specific questions to be > addressed. If the practitioner fails to ask for information you think > might help in the diagnosis, feel free to add it! I've has occasion when > I diagnosis something and at the conclusion of the visit, he/she adds a > "by the way, it also happens when.......". And that little clue throws > out the first diagnosis. I thought I was doing that, but I think some of what I was describing was not taken seriously. Maybe it's because what I have always been describing is blurred peripheral vision, not complete lack of it. I described it as looking through a dark layer of vaseline. I don't know, maybe that's not the way most people describe their sense of vision loss. > Re: FDT. I don't think it correct to state that it is a superior field > testing device. Like all computer-assisted field testing devices, it has > its strengths and weaknesses. If one machine fails to provide reliable > data, we use another. Even if it does provide excellent quality data, > it's not unusual to re-test on a different machine with a different > protocol. (I use one all the time, every day.) > > LB, O,D. > >>In some ways glaucoma can be one of the most difficult things to test > > [quoted text clipped - 45 lines] > > A "myopic" optic nerve isn't quite the same thing as a "glaucomatous" > optic nerve. But to answer your question, it is not always possible to > tell a nerve is damaged just by looking at it - myopic or otherwise. The > fact that your optic nerves had not changed suggests (but certainly > doesn't prove) that there is no glaucoma. Thank you. If I understand correctly, what you and LarryDoc are saying is that a doctor can usually tell if an optic nerve looks suspicious, but not always. So when the optometrist, the ophthalmologist, and the retina specialist all say they didn't observe any damage, it's possible they all just missed it. > > Even the same test repeated over time > > [quoted text clipped - 29 lines] > resembled those of someone with cataracts, then that's a different > pattern, and so no wonder your optometrist didn't immediately suspect > glaucoma. If you don't have cataracts, and your visual fields don't > resemble glaucoma, then you start to wonder what else may be causing > your peripheral blur... especially given its fairly rapid progression. My visual fields on the Humphrey FDT used by the optometrist resembled someone with dense cataracts--so she said. But I was specifically asking her to look for signs of glaucoma, so I was somewhat reassured when she told me she saw no evidence of it. My visual field done at the ophthalmology clinic--I don't know what kind it was, one of the ones with lights on white background--did show a defect characteristic of glaucoma. That's why my retina specialist is now telling me that's the likely answer, although it might not be. > >>Normal-tension glaucoma is even harder to diagnose, as one of the > > [quoted text clipped - 26 lines] > continued to deteriorate because in fact it was caused by a brain tumour > and not glaucoma, then you'd be more than a little upset! Yes, but I'm already upset that it wasn't detected earlier when I had less vision loss. I suppose the reason there wasn't much sense of urgency is that you are both saying glaucoma normally progresses slowly--even in the advanced stage, I take it? > Have you actually formally been diagnosed with glaucoma, or was this > just one possiblity that has been suggested to you (or, have you done a > self-diagnosis over the internet)? Because your story is not totally > consistent for normal-tensive glaucoma. I don't mean to accuse you of > anything, I just wonder whether you have jumped to this conclusion > yourself when in fact there may be another cause. Okay, I will explain completely. I have not yet been formally diagnosed. I see the glaucoma specialist in a couple of days. My retina specialist referred me to him last week, saying that he no longer thinks the vision loss is due to the PVD--because it should have resolved by now-- and that normal tension glaucoma is the more likely reason. As with most patients, the waiting to find out what's going on is agony, and I am trying to find out all I can so that I can brace myself for what is likely to be bad news no matter what. I am sure the GS will test for other causes, given the rapid progression. I am filling the time in waiting to learn as much as I can. > >>Having said all of this, if your glaucoma is advanced enough that you > > [quoted text clipped - 21 lines] > > I agree with LarryDoc that everything doesn't quite "add up" here and > neurological testing might be a good idea. And beware of internet diagnoses! > > Dom I fully expect the GS to refer me to the ophthalmogy neurologist as well. If he doesn't, I will be asking why not. I have also scheduled a consult with another GS at another eye clinic, for later this week, so I am certainly not relying on internet diagnoses. I just want to get an idea of what the various diagnoses might be that I should expect--right now advanced NTG seems the frontrunner, but having lost vision due to not asking enough questions, I want to be better prepared now. I feel pretty stupid believing for the last few months that my burred and darkening vision was going to get better in time, because that's what my RS and his colleague kept telling me. Now all of a sudden I am learning that not only will it not improve, but more than likely keep getting worse, so I do feel greatly compelled to ask a lot of questions of a lot of people and not be so naive when it comes to accepting a doctor's diagnosis. NTG can be a very elusive diagnosis. Since the pressures are "normal," the diagnosis hinges on the appearance of the optic nerve and the visual fields. BTW, a large nerve has a large cup. Everybody has the same number of nerves, and if they are densely packed, then the cup will be small. If they are spread out, the cup will be large. Do you have any other health issues, such as low blood pressure, or migraine headaches? DrG I wish to add that visual estimates of cup-to-disc ratio are notoriously unreliable. This is why there are now $50k instruments available to measure the cup-to-disc ratio and the nerve fiber layer, and those are hardly affordable except in the high volume glaucoma practices. There are other characteristic changes of the glaucomatous optic nerve that are pressure-induced, such as vertical elongation, and thinning of the rims where the nerve fibers are less dense. However, those characteristics may not be present in a nerve that is undergoing damage from a different mechanism. The mechanism for NTG is poorly understood. DrG > I wish to add that visual estimates of cup-to-disc ratio are > notoriously unreliable. This is why there are now $50k instruments [quoted text clipped - 10 lines] > > DrG Thank you. I think you are saying that a nerve undergoing damage from NTG may look normal to OD's and ophthalmologists. That gives me some idea why I have been told all along that my optic nerves look healthy while I continue to lose more and more of my visual field. I am just trying to understand how I have suddenly come to be in such a terrifying condition. > Thank you. I think you are saying that a nerve undergoing damage from > NTG may look normal to OD's and ophthalmologists. That gives me some > idea why I have been told all along that my optic nerves look healthy > while I continue to lose more and more of my visual field. I am just > trying to understand how I have suddenly come to be in such a > terrifying condition. Sorry but I am going to chime in here at this late stage with a few remarks that might seem a little pointed. I am not trying to offend anyone. I do not understand what actually makes you so certain that you have glaucoma. As others have told you the diagnosis is quite complicated. After all, you have seen an OD and a retinal subspecialist multiple times and despite their best efforts and testing they have never diagnosed you with it. All that you seem to be able to present is that you notice increasing amounts of peripheral blur that have come on rapidly. This is not typical of glaucoma as you were already informed from your doctors. I believe, as I think that others do in this forum as well, that the real problem is probably something else. While I commend you on your efforts to research information about your health problems I think you have rushed to a diagnosis that is probably not correct. To quote a cliche, "you know just enough information to be dangerous." You seem to be wanting to assign blame to health care providers that know more than you about this condition when you haven't even been proven to have glaucoma. I will warn you about this-- if you keep going around to eye doctors stating your complaints and your convictions you will undoubtedly find one who will tell you that you likely do have glaucoma and will treat you for it. After all, it seems like thats what you want to hear. Also, its a difficult diagnosis so somebody mighty just decide to err on the side of safety and treat you for it anyway. I suggest you go with an open mind to a glaucoma specialist, and possibly also to a neurologist. Let them do the testing and the explaining and ask all the questions you want. Try to be the patient, but not the doctor. Give them information and a description of your symptoms but don't try to interpret the test results for them. I know this is scary for you but don't jump the gun on diagnosing yourself and blaming others who have tried to help you. PS-- IMHO, FDT measurements are not very reliable. While the technique is a good screening tool for glaucoma (if you have glaucoma, you will almost certainly give an abnormal FDT result) it also gives a very high rate of false positives. MANY people with normal vision produce abnormal FDT results due to binocular rivalry, cataracts, floaters, and god knows what else. Nothing can bet a good old Humphrey 24-2 SITA coupled with retinal tomography. And of course a careful optic nerve head evaluation > Sorry but I am going to chime in here at this late stage with a few remarks > that might seem a little pointed. I am not trying to offend anyone. [quoted text clipped - 8 lines] > believe, as I think that others do in this forum as well, that the real > problem is probably something else. Thank you so much for your reply. What makes me pretty certain I have glaucoma is that my retina specialist, after months of telling me my visual loss was due to a collapsed vitreous, finally agreed to order a visual field test (not the FDT kind I had at the OD's office. I already knew I had significant field loss, but he said diagnosis depends on the pattern of the loss. He called me the next day to tell me the test showed field loss "suspicious of glaucoma" and that I should make an appt. with the glaumoca specialist. You are right, he did explain why he had not thought it could be glaucoma previously, and he did say maybe it's not, but that it's the most likely cause of my vision loss. Originally I saw increasing amounts of blur at the perpiphery and as this progresed, the densest areas have become darker with less and less perception of detail or light. Maybe my mistake has been describing this as blur instead of an increasing loss of detail or a kind of dimming. > While I commend you on your efforts to research information about your > health problems I think you have rushed to a diagnosis that is probably not > correct. To quote a cliche, "you know just enough information to be > dangerous." You seem to be wanting to assign blame to health care providers > that know more than you about this condition when you haven't even been > proven to have glaucoma. No, I haven't, but I fully fear I will be tomorrow. If you are saying I ought to expect a different diagnosis, in some ways I'm glad to hear that. Maybe in relating all this, I have been stressing the details that don't fit with the usual progression of glaucoma because I am partly in denial. I would be very glad to find out that none of the health care providers who examined me were mistaken. > I will warn you about this-- if you keep going around to eye doctors stating > your complaints and your convictions you will undoubtedly find one who will > tell you that you likely do have glaucoma and will treat you for it. After > all, it seems like thats what you want to hear. Also, its a difficult > diagnosis so somebody mighty just decide to err on the side of safety and > treat you for it anyway. Thank you, for making me aware of it. I've spent the past five months believing my visual loss was *not* due to glaucoma, since my doctors reassured me. It's not that I wanted to hear that it is--I certainly didn't--but if what I'm experiencing is permanent vision loss, I want a diagnosis right away that will stop the loss. Naturally. I've wasted months losing vision thinking in time the situation would resolve on its own, since that's what both my RS and another RS in the same practice told me. > I suggest you go with an open mind to a glaucoma specialist, and possibly > also to a neurologist. Let them do the testing and the explaining and ask > all the questions you want. Try to be the patient, but not the doctor. > Give them information and a description of your symptoms but don't try to > interpret the test results for them. Thank you. I've really not even been tested for anything yet, just the visual field tests. If the GS does not recommend I see the ophthalmalogy neurologist there at the hospital, I will insist. > I know this is scary for you but don't jump the gun on diagnosing yourself > and blaming others who have tried to help you. Yes, I am diagnosing myself, in terms of wanting desperately to know what to expect and what the ramifications are, and what the prognosis will be to save what sight I have left. This is my way of dealing with the agony of waiting to find out. I know waiting a week to see a specialist is no big deal to the doctor, but it can be a mightly long week to the patient. > PS-- IMHO, FDT measurements are not very reliable. While the technique is a > good screening tool for glaucoma (if you have glaucoma, you will almost > certainly give an abnormal FDT result) it also gives a very high rate of > false positives. MANY people with normal vision produce abnormal FDT > results due to binocular rivalry, cataracts, floaters, and god knows what > else. Nothing can bet a good old Humphrey 24-2 SITA coupled with retinal > tomography. And of course a careful optic nerve head evaluation. I think the visual field test I had at the hospital may have been the Humphrey 24-2. I think the one they are going to give me tomorrow may be a threshold test. But since I can obviously see a lot of vision loss, I already know I do not have normal fields. I think on the FDT, the reasons I had such poor and inconsistent results were many that you mentioned--large floaters in the affected eye, and binocular rivalry because with my good eye covered, I can still percieve the floaters in the other eye. And frequently the screen just goes dark when viewed with my good eye, since my bad eye is dominant. I've been told that shouldn't affect visual field testing, and neither should floaters, but I have a large Weiss ring floater that tends to settle just beside my point of fixation, so it's hard for me to believe that wouldn't show up as a defect. Thank you. I just hope I find out what's wrong soon, and that something can be done to stop the loss of vision before it's too late. in my opinion you need a positive Humphrey 24-2 or 30-2 SITA Standard visual field result on at least two separate appointments to say that visual field tests show you have glaucoma. Visual field results can be irratic so they need to be replicated. I agree that FDT is a screening tool only. If your FDT result was normal I would think you were likely clear, but it is very common for there to be false positive results. You also agree that you need to get Retinal tomography testing. Either Hiedelberg or GDX. Any glaucoma specialist worth their salt has one of these apparatuses now. They are invaluable for diagnosing glaucoma. Glaucoma is a tricky diagnosis. You basically have to weigh many test results and risk factors to make a good diagnosis. Have you been tested for MS? It sometimes gives blurry peripheral vision. It can come on quite quickly as Optic Neuritis. This is probably why the previous poster suggested you see a neurologist. You would rather have glaucoma! > in my opinion you need a positive Humphrey 24-2 or 30-2 SITA Standard > visual field result on at least two separate appointments to say that > visual field tests show you have glaucoma. Visual field results can be > irratic so they need to be replicated. Thank you. I'm having a second one today. I already know I have visual field loss since it's advanced enough to be obvious to me even with both eyes open, but I guess you are saying the second one might not show a pattern typical of glaucoma. > I agree that FDT is a screening tool only. If your FDT result was > normal I would think you were likely clear, but it is very common for [quoted text clipped - 3 lines] > Hiedelberg or GDX. Any glaucoma specialist worth their salt has one > of these apparatuses now. They are invaluable for diagnosing glaucoma. I assume the GS will do that. > Glaucoma is a tricky diagnosis. You basically have to weigh many test > results and risk factors to make a good diagnosis. [quoted text clipped - 3 lines] > probably why the previous poster suggested you see a neurologist. You > would rather have glaucoma! I've not been tested for MS, but I assume the GS will order an MRI since it's normal tension glaucoma with rapid progression. But from what I've read, optic neuritis would have resolved on its own by this time--it's been five months since I noticed symptoms. As for blurry peripheral vision, I'm still not sure because no actually answered this question, but doesn't visual field loss from glaucoma often start as areas of loss of acuity in the peripheral vision? That's what I'm describing as blurred. I know you can also have blind spots, but I'm wondering if my symptoms have been confused by the various eye health professionals I've seen because I keep complaining of blurry vision that is extending increasingly down into my central vision. Maybe I've not been describing the visual loss properly. I must admit that in over 20 years of practice, nobody has come into my office complaining of blurred peripheral vision. Nobody. Even patients with demonstrable peripheral field loss have never said that they noticed this. However, I do remember a gentleman with a superior absolute scotoma just above the midline stating that he had begun to notice that his golf ball disappeared after he hit it. DrG > > in my opinion you need a positive Humphrey 24-2 or 30-2 SITA Standard > > visual field result on at least two separate appointments to say that [quoted text clipped - 42 lines] > vision that is extending increasingly down into my central vision. > Maybe I've not been describing the visual loss properly. > I must admit that in over 20 years of practice, nobody has come into my > office complaining of blurred peripheral vision. Nobody. Even [quoted text clipped - 4 lines] > > DrG Well, I don't have a diagnosis yet because my GS ordered an OCT, which I had today and he's not in until tomorrow. He mentioned something about the optic nerve or rim looking "thin" so from what I've read, that does indicate glaucoma. However, he said the visual field defect (it was pretty much the same on both field tests)is not typical of glaucoma. He also said that based on the field test I should not be noticing so much visual disturbance as I am. The field test shows a defect on the superior periphery from about the ten o'clock position to the two o'clock position, with a little spur at the one o'clock position. It doesn't show relative defects as close to the central vision as I see them. My IOP in the affected eye was 15, and 18 in the normal eye. I wonder if it is common to have such a disparity of pressures between eyes. I am also worried that if it is NTG, with a pressure of only 15 now without treatment, it will be hard to get it low enough to stop progression. > > I must admit that in over 20 years of practice, nobody has come into > my [quoted text clipped - 18 lines] > position. It doesn't show relative defects as close to the central > vision as I see them. I think you need to sit down and take a deep breath. I agree with the specialist regarding the visual field defect. However, if a thin rim means glaucoma, then there are a lot of undiagnosed myopic glaucoma patients walking around out there with normal visual fields. "Thin" is a relative term, and no more signifies glaucoma than a C/D ratio of 0.6 means glaucoma. > My IOP in the affected eye was 15, and 18 in the normal eye. I wonder > if it is common to have such a disparity of pressures between eyes. I > am also worried that if it is NTG, with a pressure of only 15 now > without treatment, it will be hard to get it low enough to stop > progression. That much disparity, if repeatable, is somewhat uncommon, but what does it mean, especially if the eye with the lower pressure has the field defect? I mean, if you were a clinician looking at the available evidence, would you say it all adds up to glaucoma? I wouldn't. It appears as though you might be a conundrum. DrG > > > I must admit that in over 20 years of practice, nobody has come > into [quoted text clipped - 25 lines] > > I think you need to sit down and take a deep breath. Thank you. Of course I am panicky about this. Your advice is the best I've gotten for days! I really do need to find a way to relax a little about this--but it's hard at first when you think you might be going blind. I agree with the > specialist regarding the visual field defect. However, if a thin rim > means glaucoma, then there are a lot of undiagnosed myopic glaucoma > patients walking around out there with normal visual fields. "Thin" is > a relative term, and no more signifies glaucoma than a C/D ratio of 0.6 > means glaucoma. Thank you. My memory is getting a little jumbled now--I was obviously stressed out at the time--but I thought the glaucoma specialist said what he was seeing in the eye did not match what the visual field test showed, and that's why he ordered the OCT and photos. I thought when he said the rim looked thin, he must have meant compared to the other eye, but the affected eye is also the most myopic one. The resident who examined me first said that optic nerve looked pale, but the GS told him it wasn't pale. Half of what I learned was from listening to the GS educate the resident. > > My IOP in the affected eye was 15, and 18 in the normal eye. I wonder > > if it is common to have such a disparity of pressures between eyes. I [quoted text clipped - 9 lines] > > DrG Thanks. The way the GS left it with me is this: "You are a glaucoma suspect but I need more information to make a diagnosis." So the next step is to hear the results of the OCT. I assume that will tell a lot about what kind of damage is going on. A superior arcuate defect that does not appear confluent with the physiological blind spot, with sudden onset of symptoms, and coinciding with a peripheral vitreo-retinal event still makes me suspicious of a vitreo-retinal cause. DrG > > > > I must admit that in over 20 years of practice, nobody has come > > into [quoted text clipped - 73 lines] > step is to hear the results of the OCT. I assume that will tell a lot > about what kind of damage is going on. Thank you. Since the OCT shows damage consistent with the visual field defect, that would rule out a vitreo-retinal cause, right? Just found out the results of the OCT. That is bad news, in my understanding--I had just a little bit of hope left that my optic nerve was not too damaged. I am pretty depressed now. > A superior arcuate defect that does not appear confluent with the > physiological blind spot, with sudden onset of symptoms, and coinciding [quoted text clipped - 98 lines] > > step is to hear the results of the OCT. I assume that will tell a lot > > about what kind of damage is going on. > Thank you. Since the OCT shows damage consistent with the visual field > defect, that would rule out a vitreo-retinal cause, right? Just found > out the results of the OCT. That is bad news, in my understanding--I > had just a little bit of hope left that my optic nerve was not too > damaged. > I am pretty depressed now. Indeed, I am sorry to hear that. However, it still sounds like you are fairly early in the progression, and with proper treatment, you should do well. Please keep us informed. DrG > > A superior arcuate defect that does not appear confluent with the > > physiological blind spot, with sudden onset of symptoms, and [quoted text clipped - 117 lines] > lot > > > about what kind of damage is going on. > > Thank you. Since the OCT shows damage consistent with the visual > field [quoted text clipped - 11 lines] > > DrG Thank you for your concern. I hope the damage can be stopped but I am not in treatment yet. The GS said the next step is to measure my IOPs throughout the day, and I'm doing that Monday. I realize there are other reasons for optic nerve damage than glaucoma, so that's what he's trying to determine. I wish he would order an MRI but I guess he needs to check other things first. I just hope some kind of treatment to stop progression will be started soon as I fear to keep waiting weeks and weeks for a firm diagnosis. In any case, thank you very much for all your input. I am getting a consultation from another GS so who knows what he may say. I suppose I need to stay hopeful. Patients typically notice things when they exceed a certain threshold. Take presbyopia as an example. The regression is linear with respect to age. Yet, most patients will insist that it came on suddenly, as if overnight. I have followed so many patients with glaucoma, including one or two with NTG. Indeed, it does take many years for visual loss to develop. On the other hand, visual field defects can develop rather quickly if the pressure spikes suddenly. The lower pressure in the affected eye may suggest a ciliary body mechanism. DrG Patients typically notice things when they exceed a certain threshold. Take presbyopia as an example. The regression is linear with respect to age. Yet, most patients will insist that it came on suddenly, as if overnight. I have followed so many patients with glaucoma, including one or two with NTG. Indeed, it does take many years for visual loss to develop. On the other hand, visual field defects can develop rather quickly if the pressure spikes suddenly. The lower pressure in the affected eye may suggest a ciliary body/anterior uveitic mechanism. DrG > Patients typically notice things when they exceed a certain threshold. > Take presbyopia as an example. The regression is linear with respect [quoted text clipped - 8 lines] > > DrG Thank you, Dr. G. Yes, the vision loss is a lot more noticeable now than it was a few months ago, because at that point with both eyes open everything still looked normal. Now I can constantly see a difference, as though the top of one lens of my glasses were smeared with vaseline. It has definitely progressed towards my central vision, and that's what's scaring me. Are you talking about uveitis? I did mention to my doctor that the affected eye is often painful, usually during the night when I sleep on that side and when I wake up in the morning. Then the soreness gradually goes away. He just said he would have to examine me when I was feeling the pain. Wouldn't the dilated eye exam show uveitis, or is there some other way to test for it? I found this interesting link on uveitic glaucoma: http://www.emedicine.com/oph/topic145.htm As long as we are considering the atypical, sleep apnea has also been linked to NTG. Anyhow, please keep us posted. DrG > I found this interesting link on uveitic glaucoma: > http://www.emedicine.com/oph/topic145.htm [quoted text clipped - 3 lines] > > DrG Thank you, Dr. G. I read the article. One thing I have been telling my doctors all along is that the affected eye frequently hurts, but none of them seem to think that was important. The sharpest pain is usually first thing in the morning when I wake up although it also happens during the night, enough to wake me up. Sometimes the eye aches all day long, sometimes it's better during the day, although that could just be because when it hurts I take aspirin, and then it often gets worse as the day goes on. At its worst, it hurts a lot to look to either side. The good eye does not hurt. I suppose the pain may be due to pressure spikes so I may know more after they take my pressures all day long Monday. If that's the case, another possible reason my glaucoma has been missed for years is that I always go for a dilated eye exam in the afternoon, so that I could function in the morning. So my IOP's have always been measured in the afternoon. At this point I still don't have a firm diagnosis from one GS; the other one basically said NTG pretty much just by looking at the visual field tests. I am still hoping one of them will order an MRI. BTW, I know you said NTG is slow and that many people don't notice something different until it reaches a certain threshold, but if two months ago, when I looked at the bottom of the computer screen and the top of the screen was blurry, but now the top is blurry just when I focus on the middle of the computer screen, it's obvious to me that it's not just that I am noticing it more. My doctors don't seem to believe me either, that it's been fast progressing, although I guess there's nothing they can can do about it at this point. Actually my retina specialist did believe me, and that's why he said he didn't think it could be glaucoma. But I sure wish he would have felt a little more urgency when a patient complains of decreasing vision. > > I found this interesting link on uveitic glaucoma: > > http://www.emedicine.com/oph/topic145.htm [quoted text clipped - 36 lines] > think it could be glaucoma. But I sure wish he would have felt a little > more urgency when a patient complains of decreasing vision. Interesting case. I would tend not to dismiss someone who presented with that level of self-observation and analysis. Anyhow, it would seem that some kind of pressure-spiking was occurring. DrG > Interesting case. I would tend not to dismiss someone who presented > with that level of self-observation and analysis. > > Anyhow, it would seem that some kind of pressure-spiking was occurring. > > DrG Thanks for your input. Was just told that my glaucoma is atypical--the GS said that the appearance of the optic nerve does not in some ways match the visual field defect. I don't know what that would mean--he just said he's going to keep a closer eye on things than he normally would. There might be pressure spiking but it must be occuring at night because daylong monitoring showed pretty steady pressures. From what I have read and has been posted here, I must be atypical in a number of ways. The GS also said that with what is showing on the visual field test, most people would not even notice a vision loss. I would like to think maybe the damage is not so bad, but I suspect it's just that I am possibly more observant of visual changes than most people and am seeing the earliest changes that glaucoma causes, lack of resolution and sensitivity. Or that's what I think after reading all the feeback posted here, for which I give thanks to all. > NTG can be a very elusive diagnosis. Since the pressures are "normal," > the diagnosis hinges on the appearance of the optic nerve and the > visual fields. BTW, a large nerve has a large cup. Everybody has the > same number of nerves, and if they are densely packed, then the cup > will be small. If they are spread out, the cup will be large. I have been told many times over my lifetime that I have large nerves/cups typical of myopia. > Do you have any other health issues, such as low blood pressure, or > migraine headaches? Not that I know of. For the past two years, I've been on 12.5 mg. hydrochlorothiazide for hypertension. My pressures had been reaching 140/90 prior to that, at least at the doctor's office, although 24 hour ambulatory monitoring showed the pressure was usually normal throughout the day. Now it's normally around 120/70. I get headaches sometimes like everyone does, but I don't believe they are migraines. Here's a neat way to test for your field defects at home. Tune your television set to an unused channel so that all you see is "snow" (a gray background with shimmering white dots). Mark the center of the screen with a black dot. At a distance of about 2 feet, cover one eye and look at the dot. If you have a field defect it will appear very clearly as a solid gray area, i.e. with no dots. The size, shape and position of the defect will be perfectly clear, and much easier to perceive compared to a print-out from a static perimetry (Humphrey) test. The sensitivity and specificity are 93.2% and 96.9%, respectively, compared to standard perimetry. You can make a rough sketch of the field defects aand re-check periodically for changes. If you do this, I would like to know how it came out. --Rich > Here's a neat way to test for your field defects at home. Tune your > television set to an unused channel so that all you see is "snow" (a [quoted text clipped - 13 lines] > > --Rich Interesting idea... but you'd have to control the distance from the TV and the size of the screen to be consistent. Where'd you get the % figure? I'd be interested to read this study. Dom That you would have to control for viewing distance and screen size? Well, of course. I wrote this from memory and got it slightly wrong, but looked it up again and found that it specified a 21-inch screen and viewing distance of 30 cm. A search with Google using "Subjective detection of visual field defects using the noise-field on a home TV set in low-tension glaucoma" will take you to the abstract in Pub Med. --Rich > > Here's a neat way to test for your field defects at home. Tune your > > television set to an unused channel so that all you see is "snow" (a [quoted text clipped - 18 lines] > > Where'd you get the % figure? I'd be interested to read this study. Actually, this method was suggested on a glaucoma support board, so I have tried it. I tried it with a 27 inch tv and a 12 inch tv. With the twelve inch, I couldn't get close enough to see any scotomas. With the 27 inch, I could see my floaters very well, but no distinct scotomas. I see some darker tendrils coming down from the top, one in the one o'clock position where I know I have a defect, and a couple more in the upper nasal quadrant. These are feathery and too indistinct for me to really be able to sketch. I think my vision loss is too diffuse to show up as distinct solid grey spots. I've read this does work very well for lots of people, but I think it works better if you have scotomas, defects surrounded by normal vision. Also, I'd think the contrast settings or the way it displays "noise" on your tv may have something to do with it. I don't get a white or light grey snow pattern; on all our tvs it's white dots against black dots. That might be another reason I can't see field defects very well this way. For those interested, I think this is called white noise campimetry and here's the link I read: http://webeye.ophth.uiowa.edu/ips/PerimetryHistory/White_Noise_Field_Campimetry.htm |
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