Clinical assessment of nystagmus
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This is being published only for educational purpose and should not be used for financial gain.
Vision
• Uniocular and binocular visual acuity checked in forced primary position. In patients with latent nystagmus the uniocular vision is checked with the other eye fogged.
• It is also checked in preferred position and other relevant gazes.
Refraction
• Objective and subjective refraction (in older children): Full cycloplegic refraction done.
• Retinoscopy in younger children.
Slit lamp evaluation:
• Anterior segment : pupil, iris, lens
• Posterior segment: Optic disc & posterior pole.
Nystagmus Evaluation
• Description on basis of: Observation of child at least for 15 min.
• Amplitude: Excursion of nystagmus, small / fine, moderate, large.
• Frequency / rate: Number of to and fro oscillations in 1 sec. Described in cycles/ second of hertz. Slow (1-2), Medium (394), Fast (>5).
• Types:
– Pendular (smooth oscillations, equal on both sides), Jerky (has slow and fast components).
– Direction is noted by the direction of the fast component.
• Conjugate / Dysconjugate: Binocular with oscillations in phase in regard to amplitude, frequency, direction is conjugate. Dysconjugate can be unilateral / bilateral. If bilateral are out of phase with regard to amplitude, frequency, direction.
• Unilateral / bilateral
• Symmetric / asymmetric and uniplanar / multiplanar
• Latent / manifest
– Null zone : position of jerk nystagmus where it cannot be elicited.1
– Neutral zone: point where direction of fast component of nystagmus changes from one side to other.
– Child assumes head posture such that eyes remain in null zone.
• Presentation of nystagmus
– Amplitude shown by slow >>, medium >>->, fast >>>>.
– Magnitude of movements: single arrow (fine movement), double arrow (median movement) triple arrow (coarse movement).
– Abnormal head posture : Face turn, head tilt, chin elevation / depression.
Fig 1: Diagram of nystagmus in nine positions of a gaze.
Arrowheads indicate direction of jerk: fast phase if on one end, pendular nystagmus if on both ends and increasing frequency with more arrowheads. Additional lines indicate increased nystagmus amplitude. The curved lines indicate torsional nystagmus.
Squint evaluation if present:
• Corneal reflex
• Cover test
• Prism cover test
2 AECS Illumination
– Binocular single vision (Worth Four Dot
Test / Bagolini Test)
– Stereopsis (TNO)
– Ocular motility
– Systemic examination: Central nervous
system & others
Investigations
Videonystagmography
It is based on tracking of the eye via video image
of it. The tracking algorithm utilizes pupil as the
target and tracks eye movement. For purpose of
archiving, data can be stored as videos of eye and /
or in conventional manner with tracings identical
to those produced by electronystagmography.
It provides details about quality of movements,
provides permanent recording of nature of
movement which can be compared with later
movements. Thus if finally helps in deciding
mode of management. It is indicated in
nystagmus, neurogenic palsies (to differentiate
from mechanical restriction), myasthenia gravis,
myopathies, supranuclear gaze palsies.
NAF : Nystagmus Acuity Fusion
It is a fusion which predicts best corrected visual
acuity possible in patients with nystagmus
on the basis of objective measurements from
eye movement recordings of their waveform
characteristics during fixation of small light
emitting diode. It combines the foveation period
per cycle and the standard deviations of both eye
positions and velocity during target foveation into
a function that is linearly proportional to best
possible visual acuity.
NAFX : Expanded Nystagmus Acuity
Function
Incorporates the time intervals of foveation
periods, their positions and velocity standard
deviations into a measure of the quality of a
congenital nystagmus waveform. It assesses the
upper limits of visual acuities of the individuals
with poor foveation capabilities.
The excursion away from the midline (in
degree of visual angle) is plotted against the
time. By convention, rightward movement is
represented as upward deflection on the graph and
leftward movement as downward deflection. The
waveform is analysed to see if each phase is linear
/ accelerating / decelerating.
Electroretinography
• Important in congenital nystagmus, done
under anaesthesia.
• 30 min period of dark adapatation is advisable
for maximum response.
• Detects retinal disease causing sensory
nystagmus e.g. Leber’s achromatopsia,
congenital stationary night blindness. It is to
be noted that the fundus is initially normal.
Fig : 2 Graphical Representation of eye movements.
Fig : 3 Videonystagmography System
Neuroimaging
Indications:
• Reduced vision, normal electroretinography
• Abnormal optic nerves
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• See-saw nystagmus, periodic alternating
nystagmus, upbeat and downbeat nystagmus.
• Imaging is done with contrast enhancement.
Attention given towards suprasellar cistern
and posterior fossa.
Management
Aims of Treatment
• To improve visual acuity by stabilising eye.
• To decrease the oscillopsia.
• To shift the null zone, if any, to primary
position.
Modalities
• Optical
• Medical
• Surgical
Optical
1. Correction of refractive error sometimes
significantly decreases nystagmus. It’s difficult
to do refraction with nystagmus and requires
considerable experience. Retinoscopy is done
in null zone if it is present.
Amblyopia therapy: Strabismus is a frequent
accompaniment of nystagmus. Occlusion
therapy is often successful in patients with
strabismic amblyopia and serves to improve
vision and decrease nystagmus. Latent
nystagmus is not a contraindication to
patching.
2. Stimulating accommodative convergence:
Overcorrecting minus lenses may improve
visual acuity at distance fixation by dampening
the nystagmus2.
3. Prismotherapy : Useful as follows
• Base out prisms may stimulate fusional
convergence (especially in congenital
motor type) & thus improve visual acuity
by dampening the nystagmus3.
• Prism with apex towards the preferred
direction of gaze helps in correcting head
posture.
• Similarly appropriate prisms can be useful
to correct vertical head turns.
• But due to optical disadvantages of prism
long term use is not recommended.
4. Galilean arrangement of contact lens and
glasses: Used to stabilize the retinal images
in acquired nystagmus and oscillopsia. It
also improves visual acuity in congenital
nystagmus4.
Medical
Drugs like gabapentin, baclofen, clonazepam,
propranolol, carbamazepine have found use in
the management of acquired nystagmus, but the
benefits last only so long as the drug is continued5,6.
Surgical
• Indications:
A. To eliminate abnormal head posture by
shifing null point.
B. To decrease intensity of nystagmus in
patients with no abnormal head posture.
• General principles of surgery
A. The null point needs to be shifted towards
primary position. For this eyes are always
to be always moved in some direction as
the abnormal head posture.
B. In presence of strabismus and abnormal
head posture due to nystagmus, the
dominant eye is operated for torticollis.
If needed the non-dominant eye can be
operated to correct strabismus.
C. Surgical therapy should be based on
greatest amount of abnormal head posture
that is measured at a distance.
• Points to be considered while planning surgery
for nystagmus:
A. Surgical intervention is useful in patients
with congenital motor nystagmus and
nystagmus blockade syndrome with a null
zone away from the primary position but
the benefits are not very remarkable for
those without one7.
B. Surgery should be performed only if
abnormal head posture causes significant
cosmetic disturbance (turn / tilt > 15°)8.
4 AECS Illumination
C. Surgery should always be performed
after 6 years of age, since spontaneous
improvement can occur in some cases.
Assessment of head posture and detection
of patients with periodic alternating
nystagmus is easier after this age.
• Surgery for nystagmus can be divided into:
A. Surgical technique for abnormal head
posture
– For face turn:
1. Face turn without strabismus
2. Face turn with esotropia
3. Face turn with exotropia
– For chin elevation / depression
associated with congenital nystagmus
– For head tilt associated with
congenital nystagmus
B. Surgical technique for nystagmus blockade
syndrome
C. Surgical technique for decreasing
nystagmus intensity
• Surgical technique for face turn:
1. Without strabismus
Kestenbaum Anderson procedure (classic
maximum): It consists of bilateral recession
– resection surgeries on all the four muscles.
Presently the augmented modified kestenbaum
procedure commonly being involved is as follows:
– Upto 30° face turn (e g. Face turn to left)
Park suggested9.
Right lateral rectus recession – 7 mm
Right medial rectus resection – 6mm
Left medial rectus recession – 5mm
Left lateral rectus resection – 8mm
– Upto 40° face turn : 40% augmentation
in above surgery recommended10.
– Upto 45° face turn : 60% augmentation
in Park’s figures suggested11.
Many other modifications have been suggested,
but all are based on the same principle. Anderson
advised only recessions and go to advocated only
resections. It has been suggested that the medial
and lateral rectus should be operated in a ratio of
2:3 and the plan adjusted according to the degree
of face trun. The augmented Anderson procedure
has been reported to correct up to 40° of face turn8.
2. With Esotropia12
Depends on degree of esotropia, the fixing eye and
the age of patient.
1. More than or equal to 35pd esotropia with face
turn and fixation with adducting eye: recess –
resect on horizontal recti of adducted eye.
2. Less than 30pd esotropia with face turn and
fixation with adducting eye: overcorrection
of esotropia with recess-resect procedure on
adducting eye and overcorrection should be
neutralised by concomitant recession of lateral
rectus of nonfixating eye.
3. Esotropia with face turn and fixation with
abducting eye: In younger patients, esotropia
should be corrected first by recessing medial
rectus and resecting lateral rectus in nonfixating
adducting eye. If required face turn is corrected
by recessing lateral rectus and resecting
medial rectus of fixing, abducting eye. In
older patients, esotropia less than 30pd, both
esotropia and face turn can be corrected by
overcorrection of nonfixating adducting eye
with recession of medial rectus and resection
of lateral rectus neutralised by concomitant
recession of lateral rectus of fixing abducting
eye. But in esotropia more than 35pd, two
surgeries, first to correct esotropia and second
to correct face turn has been recommended.
3. With Exotropia12
1. Face turn with exotropia and fixation for
distance with adducted eye: Recommended
procedure is overcorrection of exotropia, lateral
rectus recession and medial rectus resection of
nonfixating eye, abducted eye to be neutralised
by lateral rectus resection & medial rectus
recession of fixing adducted eye.
2. Face turn with exotropia & fixation for distance
with abducted eye : Recession of lateral rectus
and resection of medial rectus of abducted eye.
Vol. XV, No.3, July Sep 2015 5
Surgical technique in chin elevation /
depression associated with congenital
nystagmus:
Chin elevation / depression occurs in patients
having null zone in elevation / depression. The
basic principle is same as that for face turn i.e.eyes
should be moved in direction of abnormal head
posture. Symmetrical surgery on all recti (vertical
kestenbaum) may be useful. Recommended
procedure by Park is:
1. For chin elevation / depression >25°
Chin elevation – bilateral 4mm resection of
superior rectus with bilateral 4mm inferior
rectus recession.9
Chin depression – bilateral 4 mm inferior
rectus resection with bilateral 4 mm superior
rectus recession.9
2. For chin elevation / depression <25°
Surgery is limited to bilateral 4mm recession
of depressors / elevators without resection of
antagonists.
Surgical technique in head tilt associated
with congenital nystagmus
Some patients have both horizontal and rotatory
components, since rotatory movement is dominant
causes head tilt rather than face turn. Principle of
correction is to rotate the eyes in the direction of
tilt, which can be accomplished by13.
Surgery on two oblique muscles:
Head tilt towards right shoulder can be
treated by:
– Weakening right superior oblique
(by tenotomy / recession)
– Weakening left inferior oblique (by
recession / any other method)
Surgery on four oblique muscles:
By Kestenbaum’s principle symmetrical surgery
on all four obliques (Torsional Kestenbaum). In
head tilt to right shoulder.
– Right eye is excycloducted by recessing
anterior and repositioning posterior aspect of
superior oblique tendon, advancing anterior &
anteropositioning posterior aspects of inferior
oblique14.
– Left eye is incycloducted by advancing anterior
and anteropositioning the posterior aspect of
superior oblique tendon, recessing anterior
portion & retroplacing the posterior position
of inferior oblique insertion.
– Dr. Pradeep Sharma has recommended
operating on the anterior half of all four
oblique by an amount of 8mm. For a head
tilt to the right shoulder, the right eye is
excycloducted by advancing the anterior
half of the inferior oblique, tenotomy of the
anterior half of the superior oblique. Likewise
the left eye is incycloducted by advancing the
anterior half of the superior oblique and doing
a myectomy on the anterior half of the left
inferior oblique.
– Vertical transposition of horizontal recti15:
Excycloduction of right eye achieved by:
– Right medial rectus – transposed downward
Right lateral rectus – transposed upward
• Slanting of insertion of all four recti: Was
advocated by Spielmann but not recommended
due to high chances of anterior segment
ischemia16.
Excycloduction of right eye (head tilt towards
right) achieved by:
Recession of temporal part of superior rectus
– superior part of medial rectus
– nasal part of inferior rectus
– inferior part of lateral rectus
Horizontal transpositioning of vertical recti:14
For head tilt towards right:
Right eye excyclotorted by: transposing right
superior rectus nasally & right inferior rectus
nasally.
Left eye incyclotorted by : transposing left
superior rectus temporally and left inferior
rectus nasally.
6 AECS Illumination
Surgical technique for nystagmus
blockade syndrome
• Recession of medial rectus and resection of
lateral rectus of converging eye17.
• Bilateral medial rectus recession with posterior
fixation sutures effective and better option than
recession – resection.
Surgical technique for decreasing
nystagmus intensity (in patients without
abnormal head posture)
Maximum recession of all four horizontal recti
(9mm bilateral medial rectus, 12mm bilateral
lateral rectus) is the best option. Fixation of lateral
rectus to lateral orbital wall was used in past to
decrease the intensity18.
References
1. Abadi RV, Whittle J: The nature of head postures in congenital nystagmus, Arch Ophthalmol 1991;
109 -216.
2. Dell’ Osso LF : Improving visual acuity in congenital nystagmus. In Smith JL, Glaser J eds: Neuroophthalmology,
vol 7, St Louis, 1973, P.98.
3. Arruga A : Applicationes de los prismas membranosos en terapeutica estrabologica. Arch Soc Esp Oftalmol
31:381 – 402, 1971.
4. Allen ED, Davies PD : Role of contact lenses in the management of congenital nystagmus. BJO 1983;
67 : 834.
5. Yee RD, Balok RW: Effects of baclofen on congenital nystagmus. In Lennerstrand G: Functional basis of
Ocular Motility Disorders, P.151. Pergamon Press 1982.
6. Rosenberg ML, Glasser JS: superior oblique myokymia. Ann Neurol 1983; 13 : 667.
7. Parks M.M: Congential nystagmus surgery. Am. Orthopt. J.23:35,1973.
8. Pradeep Sharma et al: A prospective clinical evaluation of augmented Anderson’s procedure for infantile
congenital nystagmus; JAAPOS Aug 2006.
9. Parks MM : Symposium : Nystagmus Congenital Nystagmus Surgery. Am Orthopt 1973; 23 :35.
10. Calhoun JH. Harley RD : Surgery of abnormal head position in congenital nystagmus. Trans AM
Ophthalmol Soc 1973; 71;70.
11. Nelson LB, Calbhourn J Het al: Surgical management of abnormal head posture in nystagmus: The
augmented modified Kestenbaum procedure. BJO 1984; 68 : 796.
12. Scholssmann, A: Nystagmus with strabismus: Surgical management. Trans. AM, Acad. Ophthalmol.
Otolaryngol. 76:1479, 1972.
13. Conrad HG, Decker W de: Torsional Kestenbaum procedure: Evolution of surgical concept.In Reinecke
RD, ed Strabismus 2. Orlando, 1982, P. 301.
14. Noorden GK von Jerkins R, Rosenbaum A: Horizontal transposition of the vertical rectus muscle for
treatment of ocular torticollis. JAAPOS 30 : 8 – 14, 1993.
15. Decker W de: Rotatorischer Kestenbaum an geraden Augenmuskeln. Z Prakt Augenheilkd 11:111, 1990/.
16. Spielmann A: The oblique Kestenbaum Procedure revisited. In Lenk – Schafer M, ed: Orthoptic Horizons.
Transcations of sixth international orthoptic congress, Harrogate, UK, June 29, 1987, P.433.