Nystagmus

Description

  • the involuntary, rhythmic movement of the eyes which is independent of
    normal eye movement
  • usually, but not always, secondary to another eye defect where central
    vision is affected. Conditions to which a nystagmus may be secondary include:
    albinism, congenital cataract, optic atrophy or hypoplasia, achromatopsia
    etc
  • some forms are not secondary to another condition, but are present without
    other vision impairments (referred to as congenital nystagmus)
  • there are several forms of nystagmus, their names describing the nature
    of the eye movement (eg jerky, pendular, rotational, undulatory, horizontal,
    vertical, oblique, roving).

Implications

  • the movement of the eye will cause the image to appear blurred
  • measured acuity will be reduced because of the student’s inability
    to maintain steady fixation. The more the eyes move and the faster they move,
    the lower the acuity
  • the student may adopt an unusual head position or head wobble to decrease
    the nystagmus
  • many students with nystagmus have a ‘null point’ or ‘null
    zone’ (ie a position of the eyes at which the nystagmus slows or ceases
    completely). For some students, the null point is reached when the eyes look
    straight ahead (ie primary position). For these students, the eye movements
    will increase when they look to either side, up or down. For other students,
    the null point may be when the eyes point up or down or to one side
  • nystagmus will decrease as the eyes converge to look at a close object
  • nystagmus will increase when one eye is covered, so that no light enters
    the covered eye
  • nystagmus will increase when the student is tired, nervous, unwell or stressed
    (eg when reading aloud, sitting tests or exams, after late nights etc)
  • the student’s visual functioning will vary according to the changes
    in the nystagmus ie the vision will worsen with any increase in nystagmus.

Suggested teaching strategies

  • ensure that all staff working with the student, including replacement teachers
    and volunteers, are aware of the vision impairment and its educational implications
  • be aware that stress or tiredness will cause the student’s vision
    functioning to decrease
  • students may not automatically discover their null point. If they have
    one, they may need to be helped to identify the best eye position and encouraged
    to use it. To locate the null point, hold a pen or small bright object in
    front of the eyes. Ask the student to hold his/her head still, and follow
    the object as it is moved from side to side, and up and down. Watch for any
    increase or decrease in the nystagmus.

In the Classroom:

  • once the null point has been identified, placement of the student in the
    classroom should take this into account.
  • if the null point is when the student looks straight ahead, then s/he should
    sit so that work is directly in front of him/her (ie centrally in the classroom)
  • if the null point is when the student looks down, then chalkboard work,
    which requires him/her to look up, will be difficult. Worksheets may be preferable
    in this case
  • the student should be encouraged to place their reading material in the
    most beneficial position in relation to their eyes and their null point
  • the student with nystagmus may experience reading problems such as skipping
    letters or lines. Tracking and scanning skills, which will be difficult for
    the student with nystagmus, can be developed and practiced. Initially, the
    use of a ‘reading window’ (a cardboard cut out which only allows
    the student to see one line of print at a time) may help the student to keep
    his/her place
  • enlargement of reading material is often necessary. This is due to the
    nystagmus lowering visual acuity and also because the nystagmus is often secondary
    to a central field loss or other impairment
  • reading material often needs to be modified eg tactual diagrams, audio
    format, braille, enlargement. For young students it may be sufficient to bring
    reading material close to the eyes
  • utilise high contrast materials eg black texta for writing, textas for
    drawing, coloured paste, using clear bold illustrations to cut around
  • bold lined paper may assist
  • always use a clean chalk board with white or yellow chalk or white board
    with black marker. Use a consistent layout when presenting information on
    a board eg homework is always found on the far right hand side of the board
  • students will benefit from desktop demonstrations ensuring visual access
    eg correct handwriting formation of a new letter, science experiment etc
  • organisational skills may require development. Developing efficient organisational
    skills will assist a student with a vision impairment eg having a large pencil
    case to store pens, calculator and visual aids; setting aside extra time to
    collect any equipment required; allowing extra time to complete visual tasks
    etc
  • additional verbal description and verification may be required to ensure
    the student has access to his/her environment eg describe a new classroom
    or excursion venue, provide verbal praise etc The student with a vision impairment
    may miss a smile of encouragement
  • the use of a personal computer (eg laptop) may be of great assistance to
    a student with a vision impairment as an alternative to handwriting and to
    reduce visual fatigue. Software is available for enlarging text and graphics,
    including icons, menus etc. Voice output is available for both IBM and Macintosh
    computers. Individual assessment of the needs of each student is essential.
    Keyboarding skills should be taught in primary school
  • strategies to reduce vision fatigue should be considered eg appropriate
    visual rests may include listening to audio tapes both for information and
    relaxation
  • students with a vision impairment often need to be taught social skills
    using a direct teaching approach. Modeling appropriate social behaviors can
    be difficult when you cannot see them accurately
  • understanding and acceptance of the student’s vision impairment,
    individual learning modes and work production methods (eg braille, computer
    etc) may be facilitated through carefully planned simulation activities and
    class education programs.

Outdoors:

  • depth perception may be poor therefore the student may have problems with
    stairs, judging distance, ball skills etc
  • students may have trouble using a monocular for distance viewing, as occluding
    one eye usually causes the eye movements to increase. The student may, instead,
    be prescribed a set of binoculars
  • students with a vision impairment may need additional orientation and mobility
    training
  • reading environmental signs eg street signs may cause difficulties.

These notes were made by the staff of the Statewide Vision Resource Centre.
They are general statements and may not apply to all students with this
condition.

See also: Nystagmus – Marion Blazé,
SVRC Education Officer (PowerPoint)