Scientific correspondence
Elevated visual motion detection thresholds in adults with
acquired ophthalmoplegia
J F Achesona, L Cassidya, E A Grunfeld* b, J A Shallo-Hoffman
b, A M Bronsteinb
a Department of
Neuro-Ophthalmology, National Hospital for Neurology and Neurosurgery,
Queen Square, London WC1N 3BG, UK, b MRC Human Movement and Balance Unit,
Queen Square, London WC1N 3BG
Correspondence to: J F Acheson jacheson{at}uclh.org
Accepted for publication 14 May 2001
AIMS
To test the
hypothesis that in patients with acquired chronic bilateral
ophthalmoplegia, abnormal retinal image slippage during head movements
would result in abnormal thresholds for visual perception of motion.
METHODSFive patients
(two males and three females) with ophthalmoplegia were included in the
study. The average age was 44 years (range 30-69 years). The aetiology
of ophthalmoplegia was myasthenia gravis (MG; n=2), chronic progressive
external ophthalmoplegia (CPEO; n=2), and chronic idiopathic orbital
inflammation. Visual motion detection thresholds were assessed using
horizontal and vertical gratings (spatial frequency) set at thresholds
for visibility. The grating was then accelerated at 0.09 deg/s2. The subject's task was to detect the drift
direction of the stimulus.
RESULTSVisual motion
detection thresholds were raised to a mean of 0.434 deg/s (SD 0.09)
(mean normal value 0.287 deg/s (SD 0.08)) for horizontal motion; and to
a mean of 0.425 deg/s (SD 0.1) (mean normal value 0.252 deg/s (SD
0.08)) for vertical motion. The difference in values for both
horizontal and vertical motion detection were statistically significant
when compared with age matched controls; p <0.023 for horizontal
motion and p<0.07 for vertical motion (two tailed
t test).
CONCLUSIONAbnormally
raised visual motion thresholds were found in patients with
ophthalmoplegia. This may represent a centrally mediated adaptive
mechanism to ignore excessive retinal slip and thus avoid oscillopsia
during head movements.
* Current address: Academic Department of Neuro-otology, Division of Neuroscience, Imperial College, Charing Cross Hospital, London, UK
Current
address: College of Optometry, Nova Southeastern University, 3200 South
University Drive, Fort Lauderdale, FL 33328-2018, USA
© 2001 by British Journal of Ophthalmology
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This article has been cited by other articles:
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Grunfeld, E. A., Shallo-Hoffmann, J. A., Cassidy, L., Okada, T., Faldon, M., Acheson, J. F., Bronstein, A. M.
(2003). Vestibular perception in patients with acquired ophthalmoplegia. Neurology
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