No CommentsNystagmus is abnormal eye movements in which the eyes shift and return involuntarily from one point to another. In nystagmus, eye movements occur in an involuntary, rhythmic and repetitive manner. These eye movements can be horizontal, vertical, rotational or a combination of these movements.
Nystagmus is an important health problem affecting 15 or 25 of every 10 thousand people in the society. People with this problem should be examined and treated with a special approach.
Nystagmus Treatment
Nystagmus treatment depends on the cause. People born with nystagmus can not be cured of this condition. Nevertheless, they may benefit from eyeglasses or contact lenses. Eyeglasses or contact lenses can help nystagmus patients see more clearly. Even though these do not fix the nystagmus, having clearer vision can help slow the eye movements.
Contact lenses have an advantage over eyeglasses because they move with the eyes. The property of contact lenses to move with the eye ensures that visual clarity is preserved even in involuntary eye movements.
Patients with better vision at close range may benefit from base-out prisms.
Sometimes, if the condition that causes the nystagmus is treated, acquired nystagmus can go away. Cessation of drug or alcohol use can be an example of this.
Nystagmus Surgery
Nystagmus can be reduced by intervening in the eye muscles in both children and adults.
Which nystagmus patients may benefit from surgery?
Patients whose vision improves, tremor reduces in a certain gaze position (null point) are the most suitable candidates for surgery. These are usually patients with infantile nystagmus.
Nystagmus patients with strabismus are also candidates for surgery.
Surgery does not cure or correct nystagmus. It just provides a more comfortable position of the head to limit involuntary eye movements. In this way, the most comfortable head position with the best vision is provided.
Types of Nystagmus
There are two fundamentally different approaches to classifying nystagmus, based on the aetiology and on the eye movement characteristics.
Classification based on eye movement characteristics
Pendular Nystagmus
Two movements occur during nystagmus. The first movement is moving away from the focused point, and the second movement is returning to the focus point. If the second movement is slow, it is called PENDULAR NYSTAGMUS.
Jerk Nystagmus
If the second movement, which is the movement of the eye to return to the focal point, is faster, we call it JERK NYSTAGMUS.
Periodic alternating nystagmus; is a type of jerk nystagmus. It is a cycle of unidirectional jerk nystagmus followed by decreases or stops within minutes and starts again in the other direction.
Disconjugate Nystagmus
In this type of nystagmus, two eyes move in two different directions. See-saw nystagmus is an example for this condition.
Classification based on aetiology
Early Onset (Childhood) Nystagmus
Infantile Idiopathic Nystagmus (Congenital Motor Nystagmus)
Congenital Motor Nystagmus is the most common type of nystagmus in young people. It is often recognized in the first few months of life but may not become evident until several years of age. We exclude other causes to diagnose this type of nystagmus.
Both jerk and pendular types are seen in this nystagmus, although pendular nystagmus can change to jerk waveform in right and left gaze.
Pendular type is less common and over time, pendular nystagmus can also transform into jerk type. Congenital pendular nystagmus is always in the form of horizontal, that is, right-left movement. Pendular nystagmus that occurs later in life, can be in the form of horizontal, up-down or rotational movements.
Congenital nystagmus patients may have a gaze position called NULL POINT, where shaking is reduced. This position may occur when the patient tilts his head, looks sideways, or moves his chin up or down.
In many patients with congenital nystagmus, the vision is greater than 50%. Stereopsis (three-dimensional vision) is present in most patients with nystagmus.
Nystagmus worsens with stress, visual attention and fixation and may worsen with illness or fatigue. Sleeping and focus on a close point reduces the intensity of the nystagmus. Thus, near visual acuity is often better than distance acuity.
Strabismus occurs in approximately 15% of patients with congenital nystagmus.
Congenital sensory nystagmus
This type of nystagmus is generally seen in infants aged 3-4 months who have an anatomical developmental disorder in the visual system,. Developmental problem in the optic nerve and albinism are the most important causes. Traumatic, metabolic, or developmental brain problems can also cause nystagmus.
Latent Nystagmus (fusional maldevelopment nystagmus)
This benign type of nystagmus is jerk-type nystagmus that occurs when only one eye is closed. It cannot be seen when both eyes open.
Spasmus Nutans
It is a mild and pendular type of nystagmus seen in the first year of life. Other characteristic features of this nystagmus are head nodding, abnormal head posture or torticollis. Spasmus nutans resolves by the end of the first decade of life though with often reduced visual acuity.
Spasmus nutans– like nystagmus has been seen with brain tumors and retinal dystrophies. Neuroradiologic investigation is warranted when there is any sign of neurologic abnormality.
Nystagmus in One Eye (Monokuler Nystagmus)
Nystagmus occurring in one eye is another condition that requires further investigation. It can be vertical or elliptical. It can be due to a problem in the optic nerve or nervous system, as well as in long-term low vision such as lazy eye and congenital cataract in one eye.
Acquired Forms of Nystagmus
Gaze-evoked Nystagmus
It is jerk-type nystagmus that occurs in lateral gaze or upgaze. It occurs with weakening or disruption of the connections between nerve nuclei and nerves that provide eye movements. In the elderly, nystagmus of mild and short duration, presenting only in one gaze direction and at the end point of the gaze, may not require investigation. However, asymmetric nystagmus lasting longer than 20 seconds requires further investigation.
Peripheral Vestibular Nystagmus (Nystagmus due to Inner Ear Diseases)
Nystagmus may occur in diseases related to the inner ear (Meniere’s disease or benign paroxysmal vertigo). These diseases are often accompanied by conditions such as hearing loss, tinnitus, nausea and vomiting. Typically, nystagmus is reduced by focusing the eyes on one point. Observation or treatment may be required in its treatment.
Central Vestibular Nystagmus
It occurs with the deterioration of the connections between the balance center in the nervous system and the inner ear nerves. This nystagmus does not decrease with focusing. It is possible to diagnose with brain and nervous system imaging tests.
