Nystagmus - Types, Causes, Symptoms, Treatment & Prognosis
Nystagmus is a vision disorder that causes the eyeballs to move back and forth or up and down uncontrollably. Most patients are born with the disease, so symptoms usually develop during infancy. It is considered to be a somewhat rare condition, affecting about 1 in a 1000 babies.
Types of Nystagmus
There are two basic types of nystagmus, optokenetic (resulting from eye problems), and vestibular (resulting from inner ear problems). These 2 types are further categorized into 5 main forms of nystagmus – manifest nystagmus, manifest latent nystagmus, acquired nystagmus, latent nystagmus, and congenital nystagmus.
Perhaps the most common type is congenital nystagmus, in which the eyes tend to move in unison when they involuntarily jerk from side to side or up and down. This is the only type of nystagmus that is not always classified as a form of strabismus, a condition characterized by the eyes' inability to work together.
Acquired nystagmus is usually caused by the effects of another disease, such as a brain tumor, multiple sclerosis, or diabetic neuropathy.
Latent nystagmus only occurs when one eye is covered, manifest nystagmus is transient (comes and goes), and manifest latent nystagmus is a continual disorder that becomes worse when an eye is covered.
What Causes Nystagmus?
Since most people are born with nystagmus it is usually considered to be a congenital condition, however the root cause is almost always neurological, even in individuals that develop the disorder later in life. Certain medications may cause side effects that induce neurological problems leading to nystagmus, and a significant head injury could also cause the condition.
In rare cases, temporary nystagmus can be brought about through hyperventilation, flashing lights, certain vibrations, and even large doses of nicotine. Because of the extensive number of causes that can lead to nystagmus, it is important to have the condition diagnosed and examined by an experienced ophthalmologist.
The main symptoms of the nystagmus are very noticeable, in that they cause a great deal of visual and emotional distress to patients, making it difficult to focus on object as your eyes continuously sweep in different directions involuntarily. In addition, not only is your vision significantly impaired, but your external appearance can be embarrassing as your eyes are in constant motion, and this often leads to social distress as well.
Unfortunately, some people with nystagmus have such poor vision that they are considered legally blind. Nystagmus makes every day routines seemed extremely difficult, and simple tasks like reading a book, riding a bike, or having a conversation with a person while maintaining eye contact can seem literally impossible.
Cases in which the nystagmus is caused by problems within the inner ear usually cause the eyes to slowly drift towards one direction before jerking back in the opposite direction. People with vestibular nystagmus tend to experience nausea and vertigo, as inner ear issues can greatly affect your balance as well. Vestibular nystagmus can be a temporary condition that occurs when fluid builds up in the ear, and it can also be a symptom of Ménière's disease.
The symptoms of nystagmus tend to decrease in severity as a person ages, however if you become tired or stressed symptoms can be aggravated.
Nystagmus Treatment and Prognosis
Patients may increase their ability to view objects by turning their head and locking their vision towards a "null point," which is a certain head position that causes the eyes to move the least, thereby stabilizing a person's vision temporarily. In some cases, injections with the drug Botox can decrease the amount of eye movements caused by nystagmus, however repeated injections are needed as the results are only temporary. Some individuals find relief by using biofeedback training to improve the neurological aspect of the condition.
People with nystagmus usually require some type of corrective lenses, however contact lenses are preferred over eyeglasses because patients eyes tend to sweep back and forth out of the line of sight that is covered by their glasses, whereas contact lenses provide clear vision from all angles.
In some cases of vestibular nystagmus it is possible to clear up the condition using a simple nasal decongestant to remove some of the fluid buildup in the inner ear.
Patients with acquired nystagmus can usually have their condition treated using medication or surgery. Surgeries are typically aimed at reducing the null position, removing the need to tilt your head as often, and reducing the cosmetic effects of the disease. Although the condition is not completely cured with medication or surgery, treatment can significantly reduce the negative impacts on various aspects of a person's life, including social, emotional, and mental wellbeing.