Nystagmus is an involuntary, rhythmic movement of the eyes. This document discusses evaluating a case of nystagmus, including defining nystagmus, classifying its types, obtaining a patient history, measuring visual acuity, amplitude, frequency, and null/neutral zones. Treatment options are also summarized such as correcting refractive error, using contact lenses, added lenses, prism correction, vision therapy, and surgery.

1. EVALUATION OF A CASE OF
NYSTAGMUS
Presenter-Himanshu Sapra
Moderator-Mrs-Sagun Jha
(Consultant Optometrist)

2. • DEFINITION
• TYPE OF NYSTAGMUS
• HISTORY
• HOW TO TAKE THE VISUAL ACUITY
• HOW TO MEASURE THE FREQUENCY
• HOW TO MEASURE THE AMPLITUDE
• WHAT IS NULL POINT
• WHAT IS NEUTRAL ZONE
• DOCUMENTATION
• TREATMENT
OBJECTIVE

3. DEFINITION
• Nystagmus is rhythmic rapidity to and fro movement of two eyes is called nystagmus
type of nystagmus described based on certain characteristics like
– rate (rapid or slow),
– amplitude ( coarse or fine),
– direction (horizontal ,
– vertical or rotational).
C L I N I C A L M A N A G E M E N T O F B i n o c u l a r V i s i o n Heterophoric, Accommodative, and Eye Movement D i s o r d
e r s(c) 2015 Wolters Kluwer. All Rights Reserved.

4. CLINICAL CLASSIFICATION
This picture taken from Association of Optometrists Artical

5. C L I N I C A L M A N A G E M E N T O F B i n o c u l a r V i s i o n Heterophoric, Accommodative, and Eye Movement D i s o r d e
r s(c) 2015 Wolters Kluwer. All Rights Reserved.

6. PATIENT HISTORY
• The usual case history must be expanded to include a number of additional questions
when evaluating patients with nystagmus.
• These include questions relating to the onset (i.e., at birth, before 6 months of age, or
specifically when).
• Association of the onset with any infection, drugs or medications, metabolic disease,
or trauma. Answers to such questions can help establish the often elusive cause of
nystagmus.

7. CONT….
• Information must be sought about observations by the parents or patient concerning
variability of the frequency, amplitude, position of gaze, or time characteristics of the
nystagmus.
• Symptoms should be assessed, especially those related to visual acuity, visual
discomfort, periodic blurring of vision, or oscillopsia.
• Except for the severely visually impaired, children with congenital nystagmus
seldom complain of visual symptoms.

8. HOW TO TAKE THE VISUALACUITY IN NYSTAGMUS
PATIENT
• Acuity testing of patients who read optotypes can proceed in the standard
manner.
• It is often more reliable to determine line or single-letter acuity with
children rather than to assess full-chart Snellen acuity.
• When visual acuity is reduced, a Bailey–Lovie chart (with logarithmic
proportionally spaced letters) or low vision chart may be needed.
• Determine acuity thresholds at distance (6 m) and at near (40 cm) for
each eye independently, as well as for binocular viewing.

9. CONT….
• Allow the patient to assume the preferred head position for
distance and near testing.
• Preschool children may need to be evaluated with hand-held
figure cards and it may not be possible to determine an exact
clinical acuity for children younger than 2 years. However, an
indication of visual ability can be determined by comparing
visual and hand–eye behavior with each eye.
• Monocular acuity differences are frequently seen in patients
with nystagmus.

10. CONT….
• Clinical differentiation needs to be between amblyopia (functionally reduced acuity in
one eye) and latent nystagmus (in which the nystagmus increases in amplitude with
occlusion).
• If there is high astigmatism, anisometropia, or strabismus— and amblyopia is
suspected—a comparison of the acuity thresholds may help make a differential
diagnosis.
• Latent nystagmus is characterized by an occlusion-induced increase in jerk nystagmus
that has a fast phase in the direction of the uncovered eye.

11. CONT….
• When nystagmus increases with occlusion, assess acuity using a method that does not
disassociate the eyes, use a plus lens and blur one eye while measuring the acuity of
the other eye.

12. TERMINOLOGIES
• Saccade/ Pursuit
• Jerk / Pendular
• Amplitude
• Frequency
• Null zone
• Neutral zone
• Conjugate/Disjugate
• Dissociated

13. DIRECTION
• PENDULAR MOVEMENT:-
• consist of to-and-fro eye movements of approximately equal
velocity in each direction . A pendular waveform can be sinusoidal
(smooth transition to the opposite direction) ortriangular (an abrupt
direction shift).
• Pendular nystagmus may be the horizontal and vertical
• JERKY MOVEMENT:-
• Jerk movements have both quick and slow components (Fig. 18.1A).
There may be intervals, known as foveations, in which the eye
movement is relatively slower for a short duration as the target
crosses the fovea and then the velocity increases.

14. • Right or left beating nystagmus.
• Upbeat or downbeat nystagmus
• Rotatory

15. AMPLITUDE
• Amplitude is the extent of excursion of the nystagmus.
• HOW TO MEASURE THE AMPLITUDE.
• The amplitude can be estimated using a millimeter ruler or a reticule in the magnifier
used to evaluate the type of nystagmus.
• As the patient fixates a target at 6 m, measurement of the overall excursion is made by
holding the ruler in front of the eye with the best acuity (either eye, if the movements
are conjugate).

16. • One millimeter of movement at the plane of the cornea translates to about 22 Δ (12
degrees of visual angle) . Therefore, if 2 mm of movement is noted, the eyes are
moving approximately 24 degrees.
• • Fine/ small : less than 5 degree.
• Medium/ moderate : 5 -15 degree.
• Coarse/ large : greater than 15 degree.

17. FREQUENCY
• • Frequency is the number of complete to and fro movements in one
second.
• HOW TO MEASURE THE FREQUENCY
• One Hertz (Hz) (1 cycle per second) means that the waveform
completes one full rotation in 1 second. Frequencies greater than 2
Hz are considered fast, and frequencies less than 1 Hz are
considered slow.
• Frequencies slower than 2 Hz can be timed with a stopwatch as the
oscillations are counted.
This picture taken from Association of Optometrists Article

18. • More rapid frequencies can be estimated with observation under low magnification of
the slit lamp.

19. NULL POINT
• The gaze position of least eye movement is the “null point” and tends to be where
vision is best. Tilting or turning the head into this direction where the movements are
least can thus optimize vision.
• NEUTRAL ZONE:-
• The neutral zone is that eye position in which a reversal of direction of jerk
nystagmus occurs and in which none of the several bidirectional waveforms, or
pendular nystagmus is present.
• It is not synonymous with the null zone.
• The null and neutral zones usually overlap.

20. HOW TO CORRECT THE ABNORMAL HEAD POSTURE
• The prisms are inserted with the base opposite the preferred direction of gaze.
• For instance, with a head turn to the left, the null zone is in dextroversion, and a prism
base-in before the right eye and base-out before the left eye will correct the head turn.
• Likewise, a compensatory chin elevation caused by a null zone in deorsumversion
will be improved with prisms base-up before each eye.
• A combination of vertical and horizontal prisms can be used when the null zone is in
an oblique position of gaze.
How to cite this article Kavitha Kalaivani N. An approach to Nystagmus management, Sci J Med & Vis Res Foun 2015;
XXXIII:138–140.

21. DOUCMANTATION OF NYSTAGMUS
PATIENT WORKUP

22. This picture taken from Association of Optometrists Article

24. TREATMENT
• Correct the refractive error
• Contact lens.
• Added lenses
 Plus adds
Minus adds
• Prism correction
• Vision therapy
Fusion Enhancement therapy
Feedback therapy for Ocular control.
• Surgery.