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J. B. Jacobs, Z. I. Wang, K. Liao, L. F. Dell'Osso; Investigating the Veracity of a Commercial, Non-Medical, Magnetic "Treatment" for Infantile Nystagmus Syndrome. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2836.
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Infantile nystagmus syndrome (INS) often leads to reduced visual acuity because of impaired ability to maintain stable gaze. Although INS cannot be cured, there are several accepted treatments - surgical, optical, and pharmacological - which have undergone rigorous scientific study for many years. Recently, advertisements have appeared for magnetized earrings that have been purported (among other claims) to improve the vision of people with INS. We cannot dismiss this out of hand, as (dubious benefits ascribed to "magnetism" aside) this could hypothetically make use of the same mechanism that we have previously shown to be a major contribution of contact lenses and other afferent stimulation of the trigeminal nerve (exteroception), similar to the mechanism (proprioception) hypothesized to underlie the therapeutic effects of nystagmus surgery.
We recorded fixation eye movements from five patients with INS, at gaze angles from 30° left to 30° right, in 5° increments. Data were sampled at 500 Hz, using digital video. Subjects were calibrated monocularly to determine alignment and viewing eye(s), and tested under four conditions: baseline, clip-on earring, purpose-sold magnet earring, and high-strength, rare-earth magnets. The patients were not told the significance of each testing condition prior to the recording session. We used the expanded Nystagmus Acuity Function (NAFX) to analyze the foveation characteristics of nystagmus waveforms and thereby determine best potential visual acuity under each test condition.
Gross visual inspection of the nystagmus waveforms showed no difference between the control condition and the other trials for any subject. No subject reported any perceptual difference between the four conditions, either visual or how their nystagmus "felt." NAFX analysis did not show significant differences between the control and any of the three ear-stimulus conditions.
Although a previous study reported positive results (reduced nystagmus) following application of magnetic earrings, the findings are questionable as there were not sufficient control or alternative testing conditions, nor was a rigorous analysis of the nystagmus waveform performed using a quantitative, foveation-based method. Instead, findings relied on patient reporting, and a visual acuity exam that may have been affected by other factors. Correcting for these factors, no demonstrable improvements in the subjects’ nystagmus was found.
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