1. Nystagmus
Panayiotis Stavrou

2. Definition
Nystagmus is an involuntary rhythmic shaking or wobbling of the eyes. The term nystagmus is derived from the Greek word ‘nystagmos’ which was used to describe the wobbly head movements of a sleepy individual.

3. Classification of Nystagmus
Doctors and researchers classify nystagmus by the characteristics of the eye movements like:
back and forth like a pendulum
slowly in one direction and then rapidly in another
laterally or vertically and by how much
how fast do the eyes move

4. Classification of Nystagmus
However there are over 45 types of nystagmus but traditionally nystagmus has been divided into two groups:
sensory nystagmus (congenital): that begins very early in life and is related to vision loss.
motor nystagmus (acquired): and is associated with neurological disorders and control of muscle function occurring later in life.

5. Congenital Nystagmus
Congenital nystagmus occurs more frequently than acquired nystagmus. It can be insular or accompany other disorders.
Types of congenital nystagmus include:
albinism, aniridia, optic nerve hypoplasia, achromatopsia, congenital cataracts, retinopathy.

6. Pendular Nystagmus
The most typical nystagmus related to vision loss during childhood is a pendular nystagmus. The eyes rotate back and forth evenly, much like a pendulum.

7. Pendular Nystagmus

8. Acquired Nystagmus
Nystagmus can be acquired later in life due to neurological dysfunction, diseases or toxicity such as:
cerebellar ataxia
thalamic hemorrhage
a head injury
stroke
multiple sclerosis
brain tumors
alcohol intoxication

9. Acquired Nystagmus
Unlike nystagmus acquired from early in life, patients with late onset nystagmus usually notice movement in their vision related to the movement of their eyes. This is called oscillopsia. Oscillopsia causes a person to have dizziness related to the new movement they experience in their vision.
Late onset nystagmus is more likely to be directional. The eye will move slowly in one direction, then quickly move back.
The nystagmus may change as the patient looks in different directions.
The unexplained onset of nystagmus in an adult may indicate a serious neurological disorder and an immediate examination is indicated.

10. Acquired Nystagmus Acquired nystagmus is subdivided into:
Horizontal Pendular Nystagmus.
Vertical Pendular Nystagmus
Seesaw nystagmus
Elliptical nystagmus
Dissociated Nystagmus

11. Horizontal Pendular Nystagmus
Most frequently, horizontal or pendular nystagmus is caused by:
central lesions involving the central tegmental tract
damage of the cerebellar nuclei
lesion near the oculomotor nuclei

12. Horizontal Pendular Nystagmus

13. Vertical Pendular Nystagmus
Vertical nystagmus occurs much less frequently than horizontal nystagmus and is often, but not necessarily, a sign of serious brain damage. T
The most common cause vertical nystagmus that frequently appears after:
pontine hemorrhage related to damage to the central tegmental tract.
toluene sniffing, glue sniffing, usually in accompaniment with cerebellar deficits

14. Vertical Pendular Nystagmus

15. See saw Nystagmus
Seesaw or jerk nystagmus is a rare binocular disorder characterized by alternating vertical skew deviation and conjugate ocular torsion. Jerk seesaw consists of torsional slow phases in one direction and quick phases in the opposite.

16. See saw Nystagmus

17. Fluctuations in Vision
Nystagmus patients often experience fluctuations in their vision. A change in the speed of the nystagmus leading to a decrease in vision can be related to:
stress
the patient’s emotional state
fatigue
the direction of view

18. The Null Position
Patients with nystagmus often find a unique position of their head and eyes that slows the nystagmus allowing them to have better vision. This is called a null position and varies with each person.

19. Treatment
Congenital nystagmus has traditionally been viewed as non-treatable, but medications have been discovered in recent years. Several therapeutic approaches are also proposed, such as:
contact lenses
drugs
surgery

20. Treatment
Gabapentin, an anticonvulsant, was found to cause improvement in about half the patients who received it to relieve symptoms of nystagmus.
Other drugs found to be effective against nystagmus in some patients include:
memantine
levetiracetam
acetazolamide

21. Treatment
Clinical trials of a surgery to treat nystagmus known as tenotomy. Tenotomy aims to reduce the eye shaking (oscillations), which in turn tends to improve visual acuity.