schiavi.qxp 24/9/08 12:51 Page 53
Surgery Nystagmus
Nystagmus – A Brief Review
a report by
Costantino Schiavi
1
and Michela Fresina
2
1. Chief of Neuro-ophthalmology, Malpighi Hospital, Bologna, and Assistant Professor of Ophthalmology, University of Bologna;
2. Research Associate, University of Bologna
Ocular nystagmus is a condition characterised by conjugate rhythmic and maximum visual potential; however, it is not fair to promise improvements
involuntary oscillations of the eyes, which may be pendular or jerky. in their visual acuity. In cases of congenital nystagmus of ocular origin
Nystagmus may be either a physiological condition – such as the associated with poor vision when there is no abnormal head position, it is
gaze-evoked nystagmus or optokinetic nystagmus – or a pathological our opinion that to reduce jerks the only possible surgery on the
condition. In the latter case, acquired or congenital pathological extraocular muscles is the supra-maximal recession of the four horizontal
nystagmus with jerky, pendular or mixed oscillations of the eye may be rectus muscles.
8–13
Patients may also benefit in terms of a reduction in
observed. Congenital nystagmus may be patent, i.e. always present in head nodding.
both binocular and monocular vision, and/or latent, i.e. present and/or
accentuated only in monocular conditions. A distinctive feature of Cases of congenital nystagmus without ocular alterations and with good
acquired nystagmus is oscillopsia. Congenital nystagmus may be vision (usually normal binocular vision) require different surgical choices.
associated with either poor vision – which is typical of nystagmus When fixed compensation strategies are present, surgery will make use
associated with ocular and oculocutaneous albinism or albinism due to of their mechanisms. We suggest the supra-maximal recession of
sensorial deprivation – or good vision. In the latter case, eye disorders are the adjugate muscles for gaze-evoked torticollis and a recession of the
usually not evident, and visual acuity can reach 20/20 in binocular vision. adjugate muscles for torcicollis in the resting position, or a recession or
resection of the four horizontal rectus muscles. Muscle surgery is not
Patients with good visual acuity and congenital nystagmus often indicated when there is no abnormal head position for compensation in
develop compensatory strategies for the purpose of benefiting from eye the primary position. In our opinion there is no indication for surgery on
positions in which nystagmic jerks are reduced or absent. eye muscles in the absence of fixed strategies for compensation, such as
Compensation may be present in the primary position, but it is obtained alternating torcicollis or torcicollis due only to distant vision or
much more often in eccentric horizontal-, vertical- or torsional-gaze compensation only for close-range vision with low distant vision. In cases
positions. When compensation is achieved in an extreme horizontal where the patient shows a blockage of nystagmic jerks in convergence
position of the gaze, there is an active block, which means that and a normal binocular vision with a good convergent fusional range, he
nystagmic jerks are masked by nervous pulses that reach the oculo- or she may benefit from artificial divergence surgery aiming to transfer
extrinsic muscles in order to keep the eye in that position. The patient the block to distant vision. There are coded surgical procedures entailing
typically has a marked torticollis. More rarely, the so-called rest either the oblique recession of all four rectus muscles of each eye
position, or Kestenbaum’s zero position, is reached when (Spielmann) or horizontal transposition of the vertical rectus muscles
compensation is achieved in a position no further than 10–15° from the (von Noorden), which can be useful in patients suffering from oblique
primary position. The electrical nystagmic activity disappears without torticollis due to oblique blockage position.
any active mechanism. In this case, torcicollis appears to be moderate.
Even less frequent are the cases where there is an oblique Recent surgical nystagmus treatment attempts include tenotomy and the
compensatory position. Regardless of the presence or absence of a subsequent reattachment of the horizontal rectus muscles at the level
horizontal or oblique block strategy, most types of nystagmus show a
reduction in the converging jerks normally associated with close-range
Costantino Schiavi is Chief of Neuro-ophthalmology at
vision that is as at least as good as or better than distant vision. Patients
Malpighi Hospital, Bologna, and an Assistant Professor of
with acquired vertical nystagmus may also sometimes assume a
Ophthalmology at the University of Bologna. He has
compensatory head posture in order to dampen the jerks and to reduce
presented papers on strabismus and amblyopia at over 20
international conferences. He serves as a Council Member of
oscillopsia. In downbeat nystagmus, the jerks usually become less the International Strabismological Association (ISA) and as
prominent or disappear when the patient gazes upwards, and patients
Secretary and Treasurer of the European Strabismological
Association (ESA).
may show a compensatory ‘chin down’ position. The opposite happens
in upbeat acquired neurological nystagmus, where patients may
assume a ‘chin up’ head posture.
1,2 Michela Fresina is a Research Associate at the University of
Bologna. She has published 26 papers in the aresa of
strabismus, pharmacologialc treatment of amblyopia and
Surgical Intervention on Extraocular Muscles nystagmus. Dr Fresina graduated with honours in medicine
Currently, nystagmus cannot be cured. Over the years, many different
from the University of Bologna in 1998, and achieved her
PhD in strabismology at the University of Rome in 2004.
surgical strategies have been attempted to improve the visual
E:
michela.fresina@libero.it
performance of nystagmic patients.
3–7
In some carefully selected cases, it
is possible to help patients and enable them to use their eyes at their
© TOUCH BRIEFINGS 2008 53
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