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Medical Forum / General / Vision / August 2005Epiretinal & Aniseikonia
I have diagnosed with an Epiretinal Membrane in my left eye. I addition to blurred vision; objects in my left eye appear to be 10-15 % larger than my right eye. My corrective lens compensate for a difference of 4%. I have chronic tension headaches centered in the forehead. This has been a ongoing problem. I get some relief from botox injections, and over-the-counter pain medication. My surgeon does not want to perform a Membranectomy until my vision is worst than 20/40 corrected in my left eye. Any suggestions or help would be appreciated. I live in the Dallas, TX area. >I have diagnosed with an Epiretinal Membrane in my left eye. I > addition to blurred vision; objects in my left eye appear to be 10-15 % > larger than my right eye. My corrective lens compensate for a > difference of 4%. So is the aniseikonia something new, supposedly caused by the membrane? I haven't heard of that. Acquired aniso is much more aggravating than congenital. If you wore a minus contact lens on the right eye and then boost the right spectacle lens by the equivalent plus, you can get much more than 4% size correction. You might also reverse everything and wear a plus contact on the left eye with excess minus in the spectacle lens. The choice depends on whether you're wearing plus or minus now, how your frame fits, which eye is dominant, which eye is healthier, and other details. It isn't usually necessary to neutralize the anisekonia exactly, or even completely. With trial lenses you can see the effect before making a special spectacle lens. If you do, keep your old lens. -MT >I have diagnosed with an Epiretinal Membrane in my left eye. I >addition to blurred vision; objects in my left eye appear to be 10-15 % >larger than my right eye. My corrective lens compensate for a >difference of 4%. > It might be helpful if you'd post your spectacle Rx along with acuities with the Rx in place. I would assume the membrane has nothing at all to do with the aniseikonia. >I have chronic tension headaches centered in the forehead. This has >been a ongoing problem. These may or may not be related to aniseikonia; are probably not related to the membrane. > I get some relief from botox injections, and >over-the-counter pain medication. So they are at least partly muscle spasm type headaches, I'd guess. > My surgeon does not want to perform >a Membranectomy until my vision is worst than 20/40 corrected in my >left eye. > Post the acuities. The membrane peel will probably give you better vision in the left eye, but may have no effect on your headaches or and will not affect the aniseikonia. w.stacy, o.d. My pre-USAF Vietnam era physical eye exam was Lt. eye 20/10 & Rt. eye 20/15. Before the epitretianl membrane, their was no headaches nor was there any difference in image sizes between the two eyes. Peeling MAY inprove the eye sight. But there is a good deal of risk involved with the peeling. IMHO the epiretinal membrance has a changed the optics causing the larger image on the Lt. side. Wearing an eye patch over the Lt. eye reduces the muscle tension in the forhead but makes for poor depth perception. Am looking for the best epiretinal surgeon in the country. OK then since I don't have any Rx data to work with, I'm going to make a couple of (large) assumptions. The maculopathy has caused the macula to move forward, making the left eye more hyperopic, so when you wear a plus spectacle lens to correct that hyperopia, you have induced aniseikonia. If this is true, the aniseikonia may be completely fixable with a contact lens on that eye. We've got some good ones here in the Sacramento area. Where are you? Most major metropolitan areas have vitreo-retinal groups. I'd go to one of those group practices that only does v/r work. w.stacy, o.d. >My pre-USAF Vietnam era physical eye exam was Lt. eye 20/10 & Rt. eye >20/15. [quoted text clipped - 13 lines] > > The aniseikonia occurs with or without glasses. Tried contacts but to no avail. Will get my prescription this week. Live in Dallas, TX. We have the vitreo-retinal groups. I would prefer a doctor with loads of experience with ERM removal. Ok then in view of what Dr. Robins posted, you don't actually have "regular" aniseikonia, but a special variety of metamorphopsia that the maculopathy caused. If I recall correctly, you can't really correct that much of an image size difference optically, nor would you want to, since it's not affecting the majority of your fields (only the central 5 degrees or so). I'm afraid your only fix is to find that special surgeon for that special, exquisitely delicate procedure. Good luck. w.stacy, o.d. >The aniseikonia occurs with or without glasses. Tried contacts but to >no avail. [quoted text clipped - 5 lines] > > On 7/25/05 4:38 PM, in article SJeFe.462$iM7.134@newssvr21.news.prodigy.com, > OK then since I don't have any Rx data to work with, I'm going to make a > couple of (large) assumptions. The maculopathy has caused the macula to [quoted text clipped - 26 lines] >> >> Actually, this is not an uncommon problem. IT IS UNRELATED TO THE MACULA MOVING FORWARD. This (central) size shift is not really aniseikonia in the usual sense - it is a metamorphopsia. What happens is the epiretinal membrane distorts the macula size, making it smaller (the usual story) or larger. If the photoreceptors are pulls towards thefova, making it smaller, the same image falls on more photoreceptors, so the image seems larger than the other eye. However, it is only in the center. Periphery is unchanged. This causes a disparity in the central image both not the periphery that locks the eye images together. This has no optical remedy, since it is not uniform across the image as in optical aniseikonia due to anisometropia, which can be helped by contact lenses or "size" lenses, as Dr. Stacy describes above. The only papers on this describe using Bangerter foils on the lens to blur the image just enough that the macula image can be ignored, without losing the use of the periphery. An ophthalmologist that I know had this, and he also placed a tiny round disk of Scotch Magic tape (the frosted stuff) in the optimum spot on the glasses to allow him to block out just the macula of that eye. David Robins, MD Board certified Ophthalmologist Pediatric and adult strabismus subspecialty Member of AAPOS (American Association of Pediatric Ophthalmology and Strabismus) I agree with Dr. Robins on the explanation of the aniseikonia associated with an epiretinal membrane (see also the abstract of a paper we wrote on this topic below). As he mentions the aniseikonia cannot be fully corrected by introducing a constant optical magnification difference, because the amount of aniseikonia changes (rather smoothly) with visual field angle. Nevertheless, partial relief seems to be possible by searching for and correcting the aniseikonia at the visual field angle that seems to bother the patient most. Gerard de Wit, Ph.D. Optical Diagnostics http://www.opticaldiagnostics.com ----------- Field dependent aniseikonia associated with an epiretinal membrane: a case study Gerard C. de Wit, Ph.D. and Cecilia S. Muraki, O.D. Purpose: Aniseikonia is a binocular anomaly in which the two eyes perceive images of different size and/or shape. It is usually assumed to be constant as a function of visual field angle (i.e. angular distance from the line of sight). This is correct for optically induced aniseikonia, such as the aniseikonia that is associated with anisometropia and probably also pseudophakia. The purpose of this paper is to show that if the aniseikonia is of retinal origin, then the aniseikonia may no longer be constant as a function of visual field angle (i.e. field dependent aniseikonia). Design: Case report, with the patient having a unilateral epiretinal membrane. Methods: The aniseikonia was measured in the vertical and horizontal direction with a customized version of the Aniseikonia Inspector software. The visual field angle was made variable by changing the dimensions of the size-objects in the direct comparison procedure. Main outcome measures: Aniseikonia as a function of visual field angle. Results: The patient exhibited good repeatable aniseikonia ranging from 23% to 2.5% for visual field angles ranging from 0.36° to 5.7°. In this range higher angles had lower aniseikonia. A control subject did not show this field dependent aniseikonia. Conclusions: Aniseikonia may vary with visual field angle due to a retinal origin such as with an epiretinal membrane. The problem with field dependent aniseikonia is that it cannot be fully corrected with conventional optics which exhibits an approximately constant magnification as a function of visual field angle. Nevertheless, by correcting 5-10% aniseikonia which was present in the visual field angle measurement range at 2° to 3°, our patient had improved visual comfort, especially for reading. ----------- > Actually, this is not an uncommon problem. IT IS UNRELATED TO THE MACULA > MOVING FORWARD. This (central) size shift is not really aniseikonia in the [quoted text clipped - 23 lines] > Member of AAPOS > (American Association of Pediatric Ophthalmology and Strabismus) |
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