Microsoft word - nystagmus.doc

Nystagmus
by Stephanie Williams
What is Nystagmus
It is characterized by an involuntary movement of the eyes, which may reduce vision or
be associated with other, more serious, conditions that limit vision.
Nystagmus has undulating movements of equal speed, amplitude, and duration, in each direction or jerky with slower movements in one direction, followed by a faster return to the original position. Movements may be horizontal, vertical, oblique, rotary, circular, or any combination of these. Generally, the faster the rate, the smaller the amplitude (and vice versa). The defect is classified according to the position of the eyes when it occurs. ● Grade I occurs only when the eyes are directed toward the fast component ● Grade II occurs when the eyes are also in their primary position ● Grade III occurs even when the eyes are directed toward the slow component. Reduced acuity is caused by the inability to maintain steady fixation. Head-tilting may decrease the nystagmus and is usually involuntary. Head nodding often accompanies congenital nystagmus. Dizziness or vertigo may be experienced if oscillopsia or illusory movements of objects occurs. Nystagmus may be induced with an optokinetic drum or through the stimulation of the semicircular canals. Congenital nystagmus of the pendular type usually accompanies congenital visual impairment. Like the corneal opacity, cataract, albinism, aniridia, optic atrophy, chorioretinitis. Nystagmus may also accompany a number of neurological disorders, and may be a reaction to certain drugs. The cause of nystagmus is unknown.
There is no known treatment
Certain types of jerky nystagmus, commonly Grade I types show spontaneous
improvement in childhood up to age 10. This type may also be amenable to muscle
surgery essentially, a repositioning of muscles to take advantage of the point of least
nystagmus, or position of relative rest.
Children with nystagmus
Tend to lose their place in beginning reading instruction may be helped through the use
of a typoscope card with a rectangular hole, to view one word or line at a time or an
underliner card or strip of paper to "underline" the line being read. As children with
nystagmus mature, they seem to need these support devices less often.
Nystagmus and Contact Lenses
Contact lenses have been shown to aid some nystagmus patients. One theory is that
the tactile feedback of feeling the contact lenses on the eyes may lead to better control
of the movement and allow the patient better vision. Another benefit of contact lenses is
that they move with the eyes and thus providing better image quality.

Balance and Binocular Vision
Patients with nystagmus may report problems with balance. Impairment to binocular vision is common with early onset nystagmus and depth perception is indirectly impaired in many patients. Nystagmus acquired later in life may cause vertigo or dizziness like effects from the sensation of motion in the vision. Nystagmus may decrease when the eyes converge to read. Low vision specialists can add prism to induce convergence artificially and thus reduce the nystagmus in some patients. Medical and Surgical Treatments
Several surgical procedures have been developed to reduce null positions and thus
improve a patient’s cosmetic appearance. Botox, botulinum toxin, has been used to
paralyze ocular muscles and thus reduce nystagmus. It has not become a practical
treatment since the effect of this drug lasts only three to four months and requires
injection into the ocular muscles under general anesthesia. Baclofen has also been
used to lessen certain forms of nystagmus. Additionally, biofeedback has also been
used to treat nystagmus.
Social Issues
Not only do nystagmus patients have vision loss, but they also are faced with cosmetic
problems from the constant eye movements and often an unusual head/eye position.
Patients may be teased about their appearance or chastised and told to hold their head
correctly.
A wealth of information about Nystagmus is available and continually
being published.

Source: http://vas.vusd.k12.ca.us/teachers/msimica/Student_Projects/Nystagmus.pdf