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LA Abel, L Tkalcevic; "Inverse Latent" Congenital Nystagmus Associated with Oscillopsia . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2658.
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Purpose:To investigate a 17-year old female subject with CN complaining of oscillopsia viewing OU and stable vision (and a marked diminution of her CN) viewing OD. She had been operated on at age 3 (by her mother's recollection) for a left esotropia; the details of neither the surgery nor the patching were recalled. She had a long-standing, emphatic complaint of oscillopsia when viewing binocularly, relieved by closing her left eye. Methods:After clinical ocular motility assessment, eye movements were recorded. Her nystagmus was analysed to determine the percentage time spent in a foveation window of ±0.5° and ±4°/s during both OU and OD viewing. Her perceptions during the recordings were noted. Results:LogMAR VA was 6/9.5 OD, 6/24-1 OS, 6/12 OU. She was orthophoric at distance and near. Lang stereoacuity was 550". Her OU waveform was pseudocycloid jerk left, 6-15° amplitude (OS was similar). OD waveform was jerk with extended foveation CN of variable direction. Examples are shown of OD motion, while viewing binocularly on left and with OD on right. Foveation periods are darker. Bars represent 1° and 1 s. Percentage time within the foveation window was 1.2% OU, 33.6% OD. Oscillopsia was constant when viewing OU or OS and absent when viewing OD. Conclusion:Binocular vision--normally much desired--is perhaps uniquely associated here with pronounced exacerbation of CN and development of nearly continuous oscillopsia. Although "inverse latent" CN--nystagmus improving with occlusion--was described by Dell'Osso et al in 1974, it has been little noted since then. Their subject had no history of strabismus. In our subject, early treatment provided her with good ocular alignment and stereopsis; however, these improvements were associated with a marked exacerbation and change in waveform of her CN, with a pronounced reduction in foveation time. Her ability to suppress oscillopsia may have depended on adequate foveation, as has been reported (eg, Abel et al, 1991). Alternatively, the mechanism for subtraction of the efference copy and retinal slip signals for oscillopsia suppression may have already become fixed by age 3 and been unable to cope with the development of binocular input. View OriginalDownload SlideView OriginalDownload Slide
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