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Medical Forum / General / Vision / March 2007Expert optical advice requested
I have aniseikonia (a disparity in image size between my eyes) associated with an epiretinal membrane, which was surgically peeled over a year ago. My main symptom has been excessive tearing in my affected eye in addition to a gradual decline in my ability to fuse. (I currently feel that I'm close to the point of experiencing diplopia.) The etiology of my condition was described in previous posts by Dr. David Robins. Apparently, the ERM distorted the size of my macula, pushing the photoreceptors toward the fovea, thereby making the image size in my affected eye about 5-10% larger than the image in my other eye. So I'm left with two central images of different sizes, with the periphery of both identical. The only "treatment" has been to create sufficient blur in the affected eye so that the larger central image is not distracting, but not so much so that the periphery is lost. Dr. Robins also mentioned the possibility of strategically placing a small disc of Magic tape on the glasses lens to block the macular image. 1) I did not become aware of the image size difference until AFTER the ERM was peeled. (My vision improved from about 20/40 to 20/20 post-surgery.) I'm assuming that this was due to the blur from ERM. However, I've been unable to create the right blur with the Bangerter foils used in the literature. The -0.3 foil reduces my acuity to 20/70 but only partially eliminates my aniseikonia symptoms. (And the loss of acuity gives me a headache and leaves me spatially disoriented. I'm reluctant to even try the -0.4 foil.) Is it possible that the foil isn't creating the right quality of blur? Then what might work? 2) I've tried the disc of Magic tape on my glasses, but it doesn't work unless my gaze is straight forward. I've been wondering whether this strategy might work better with toric contact lenses. My current lenses are bifocal and are truncated on the bottom to prevent rotation. Would it work better with a monofocal truncated contact lens? How could this type of occlusion be accomplished? 3) I had post-vitrectomy cataract surgery, and I'm in the process of developing PCO in my affected eye. The PCO might provide the needed blur for a time (before creating blindness in the eye). Is it possible to have a YAG laser procedure that would only partially eliminate PCO? It's definitely a downer to have a rare disorder with no solutions (as yet). I'm hoping that corrective lenses for macular-related aniseikonia might help. (They are currently in the experimental stage.) Until then, any suggestions/ideas would be very much appreciated. >I have aniseikonia (a disparity in image size between my eyes) >associated with an epiretinal membrane, which was surgically peeled [quoted text clipped - 11 lines] >periphery is lost. > I think you should go for the best correction in both eyes if you want to maintain fusion, and hope for the best. If you're ready to discard binocularity, then you can block out the worst eye (the non peeled eye?) with a variety of methods, including patching, opaque center CL, etc. >1) I did not become aware of the image size difference until AFTER >the ERM was peeled. (My vision improved from about 20/40 to 20/20 [quoted text clipped - 7 lines] >what might work? > I'm against this if you want to use both eyes. >2) I've tried the disc of Magic tape on my glasses, but it doesn't >work unless my gaze is straight forward. I've been wondering whether [quoted text clipped - 3 lines] >lens? How could this type of occlusion be accomplished? > You can get a contact lens with a black opaque center. Again, tossing binocularity out the window. >3) I had post-vitrectomy cataract surgery, and I'm in the process of >developing PCO in my affected eye. The PCO might provide the needed [quoted text clipped - 3 lines] > > Yes, but not selectively so that it would only affect the macula, unfortunately. >It's definitely a downer to have a rare disorder with no solutions (as >yet). I'm hoping that corrective lenses for macular-related [quoted text clipped - 3 lines] > > There is no physical way to do it optically, which is why I'm voting for trying to learn to live with it. Remember, if anything happens to your good eye, you will want to use the peeled eye as your main eye. In fact, if the best corrected vision is now in the peeled eye, you might try occluding the other eye if occlude you must. Dr. Stacy, if it were possible for me to maintain fusion without resorting to occlusion, it would definitely be my first choice. (My uncorrected acuity in both eyes is 20/20 for distance vision.) The two doctors I have consulted (one by email) were both surprised that I didn't already have diplopia, given the estimated percentage of my aniseikonia. Currently, distant moving images are occasionally beginning to break apart. Actually, it was my sense of imminent diplopia that led to my self-diagnosis of macular-related aniseikonia; my doctors had attributed my excessive tearing to a dry eye condition. And from everything I've read, diplopia of this origin cannot be controlled with prisms. So I feel forced to do something now, and I'm hoping to expand my range of options. It's just the central (macular) image that I want to blur, not the periphery. I hate the result of the -.3 occlusion foil; so I'm going to contact my optometrist to see about what can be done with a contact lens. >Dr. Stacy, if it were possible for me to maintain fusion without >resorting to occlusion, it would definitely be my first choice. (My [quoted text clipped - 9 lines] >now, and I'm hoping to expand my range of options. > Well I'm not sure I understand what you mean by "beginning to break apart". To me it says that they have not yet broken apart, so you don't have diplopia. You may or may not get diplopia in the future, nobody knows that. However, it is very possible that you ALSO have a binocular imbalance. If you have both, the binocular imbalance part CAN be helped with prism. >It's just the central (macular) image that I want to blur, not the >periphery. I hate the result of the -.3 occlusion foil; so I'm going >to contact my optometrist to see about what can be done with a contact >lens. > Nothing can be done with a CL that would obscure the macula without concurrently obscuring most if not all of the retina. You can do it with glasses, but only through one position of gaze (the one where your macula, the occluding spot and the object you are looking at are all lined up perfectly. Move the gaze 1 mm off that spot, and you're occluding some off-macula spot. The only way to do it would be to have an exotic eye tracking device that would move the occluder spot with the exact movement of your eyes, and a technological marvel it would be (it would also have to be miniaturized and wearable). I'd experiment with some prisms first in the hope that there is some binocularity issue at work. There is only one situation where I always have diplopia. It happens when I'm looking at the red zero of my carbon monoxide detector in a very dark room. I suppose it's because against a black background, there are no peripheral cues for fusion. But over the past couple of months, I've noticed that distant moving images have begun to develop a ghost, and a couple of times recently the image did double. From what I've read, most people with my condition do have diplopia. But there's been so little about this in the medical literature. I set up an appointment with my optometrist to look into occlusion with a contact lens. It can't be much worse than those Bangerter foils. Maybe he'll have some other ideas. I'm pessimistic, though, about the use of prisms. Per Dr. Robins' post (and other online info), prisms aren't effective for diplopia secondary to macular- related aniseikonia. I very much appreciate all the input I've received here. It's very isolating to diagnose yourself with a rare disorder that most eye care professionals have never even heard of, let alone know how to treat. > There is only one situation where I always have diplopia. It happens > when I'm looking at the red zero of my carbon monoxide detector in a > very dark room. I suppose it's because against a black background, > there are no peripheral cues for fusion. Could be, but doubtful. Try closing one eye at a time and looking at that display. You could be getting monocular diplopia. But over the past couple of > months, I've noticed that distant moving images have begun to develop > a ghost, and a couple of times recently the image did double. From > what I've read, most people with my condition do have diplopia. But > there's been so little about this in the medical literature. Again, the ghosting could be a monocular phenomenon. Be sure to alternately cover each eye COMPLETELY when observing this. > I set up an appointment with my optometrist to look into occlusion > with a contact lens. It can't be much worse than those Bangerter > foils. Maybe he'll have some other ideas. I'm pessimistic, though, > about the use of prisms. Per Dr. Robins' post (and other online > info), prisms aren't effective for diplopia secondary to macular- > related aniseikonia. Have him rule out monocular diplopia and heterophoria, and better yet, fixation disparity. Of course I agree that prisms don't work for some things, but you don't yet have a definitive diagnosis, so you're guessing. > I very much appreciate all the input I've received here. It's very > isolating to diagnose yourself with a rare disorder that most eye care > professionals have never even heard of, let alone know how to treat. I think most of us have heard of macular peels, aniseikonia, diplopia (both monocular and binocular varieties), etc. Get that diagnosis nailed down before you make up your mind about how to treat it, if at all. Definitely binocular diplopia in all instances. In a dark room, my right (affected) eye reliably drifts in a southeast direction. The estimated difference in image size between my eyes (first observed post-vitrectomy) of about 5-10% makes the diagnosis hard to overlook, IMO. I mentioned it to my retinal surgeon during several post-op visits, yet he never seemed to think it was significant. At our most recent appointment, he suggested that I use an eyelid cleanser to treat my excessive tearing. I've also mentioned the image size difference to my cataract surgeon and my optometrist, but both also attributed my tearing problem to dry eyes. I have a medicine cabinet filled with dry eye treatments (both prescription and OTC remedies), none of which helped the tearing. But it was what I perceived to be a decline in my ability to fuse that got me doing online research. > Definitely binocular diplopia in all instances. In a dark room, my > right (affected) eye reliably drifts in a southeast direction. Sounds like exotropia, definitely a binocularity problem that can often be helped with prism. The > estimated difference in image size between my eyes (first observed > post-vitrectomy) of about 5-10% makes the diagnosis hard to overlook, > IMO. Well, the aniseikonia might precipitate the eye turn, sort of like the straw that broke the camel's back, but the eye turn and it's associated diplopia is quite treatable with prism, EOM surgery, vision therapy, or any combo of those. I mentioned it to my retinal surgeon during several post-op > visits, yet he never seemed to think it was significant. At our most > recent appointment, he suggested that I use an eyelid cleanser to [quoted text clipped - 4 lines] > none of which helped the tearing. But it was what I perceived to be a > decline in my ability to fuse that got me doing online research. The tearing is very likely more related to dry eye. Have you tried Restasis for at least a month? The diagnosis of aniseikonia secondary to ERM has (unfortunately) already been confirmed by two doctors through email correspondence as well as by the one practitioner in my area who is knowledgeable about it. (He says he sees about one or two cases a year.) He gave me the occlusion foils a couple of days ago, which are the only "treatment" described in the literature (that I could unearth.) There's such a high level of expertise evident in some of the posts on this forum that I was hoping that someone out there might know of a better optical solution. I'm disappointed to learn that it's not possible to blur only macular vision using a contact lens; that alternative seemed to have potential. Yes, I've tried Restasis (and a dozen other dry eye remedies) over the past year. Excessive tearing is also a symptom of aniseikonia, which is probably why none of the remedies have helped. At the present time, my best bet may be corrective lenses for field-dependent (i.e., variable across central vision due to macular disease) aniseikonia, which are currently experimental. > The diagnosis of aniseikonia secondary to ERM has (unfortunately) > already been confirmed by two doctors through email correspondence as [quoted text clipped - 14 lines] > variable across central vision due to macular disease) aniseikonia, > which are currently experimental. Why can you not obtain a soft contact lens with a central occluder? DrG My goal is to blur the central (macular) image in the affected eye sufficiently so that the difference in image size between my eyes can be ignored, but not so much that the periphery is lost. My epiretinal membrane did a fine job of this, blurring my central vision to about 20/40. I don't want to lose all vision in the eye. I'm seeing my optometrist today to see what's possible in this regard. But from Dr. Stacy's post, occlusion with a contact lens is all or nothing. In that case, I'd be better off with a foil on my glasses that blurs the eye to 20/70. > My goal is to blur the central (macular) image in the affected eye > sufficiently so that the difference in image size between my eyes can [quoted text clipped - 5 lines] > that case, I'd be better off with a foil on my glasses that blurs the > eye to 20/70. These occluder lenses are totally custom, i.e. the black spot in the center can be of any diameter. DrG Sounds good. In case my optometrist hasn't heard of them, is there a particular manufacturer/brand? I assume that the degree of occlusion is (unfortunately) complete. > Sounds good. In case my optometrist hasn't heard of them, is there a > particular manufacturer/brand? I assume that the degree of occlusion > is (unfortunately) complete. Adventure In Color Technology does this work on a custom basis. DrG > Why can you not obtain a soft contact lens with a central occluder? You can get the occlusive spot smaller than the pupil, but the problem is the light passing around the spot will end up not only on the peripheral and paramacular area, but into the macula as well. In fact, such a lens will act very much like a central cataract, and we all know that those don't block the macula selectively... > I have aniseikonia (a disparity in image size between my eyes) I'm not an expert, I'm a lay person, but I've been there and done that, although for a different reason. I was plano in one eye and -10D in the other. Two solutions come to mind, neither very good. With glasses, you can get one lens frosted. This blocks the vision. I don't know if this option is available with contacts. The other is to wear a patch. I've done that. The kids look at you funny. The adults pretend not to notice. Neither my wife nor I see out of both eyes, for different reasons. At some point the brain just learns to ignore the vision from the poorer eye, and the double vision goes away. I understand that your problem is completely different from what I had. If I wore contacts, then I had no problem. At some time in the evening, I took out the contacts and switched to glasses. I had several years of double vision. It was OK, I was done with the day, I could read and I could watch tv. Eventually, my brain figured out that when I wore glasses, ignore the image from the right eye. >the image size in my affected eye about 5-10% larger than the image in >my other eye. So I'm left with two central images of different sizes, >with the periphery of both identical. I don't know if this will help but a spectacle lens in conjunction with a contact lens can easily provide 10% minification or magnification. Regards, Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical Wauwatosa Wi. ~~~~~~~~~~~~~~~~~~ "Science is a way of trying not to fool yourself." - Richard Feynman |
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