Nystagmus is a type of uncontrolled eye movement affecting approximately one in every 2,000 individuals, it is characterized by alternating smooth eye movement in one direction and saccadic (abrupt, short) movement in the other direction. Movement is usually from side to side but, sometimes movement can be up and down or even circular. Nystagmus is not painful and does not lead to progressive loss of vision
Types of Nystagmus
There are more than 40 different types of nystagmus but they are usually classified into two basic categories:
1. Nystagmus present from early in life, is known as early onset nystagmus, or congenital nystagmus, it often accompanies vision loss acquired at birth or soon after and may be one of the first signs that a child has a loss of vision.
2. Nystagmus which develops later in life is called Acquired Nystagmus.
Causes of Nystagmus
1. Early onset nystagmus: Pediatric Nystagmus may be caused by a problem with the eyes or the visual pathways leading from the brain to the eyes. This type of nystagmus is usually first observed between 6 weeks and 8 weeks of age and can be associated with albinism, optic nerve problems or retina problems. There is likely to be a genetic factor and in fact doctors have recently announced a breakthrough in the discovery of a gene associated with nystagmus which holds great promise for future treatments.
Many patients do not have any eye, brain or other health problem and in these cases the condition is known as congenital idiopathic nystagmus (meaning that the nystagmus starts early and the cause is unknown). Nystagmus associated with albinism has characteristics similar to idiopathic nystagmus but usually is absent until after age 2 months. Nystagmus can also be found in children with Down’s syndrome.
2. Acquired nystagmus: Nystagmus can be acquired later in life due to neurological dysfunction such as a head injury, multiple sclerosis or brain tumors. Nystagmus can also be caused by lesions in the cerebellum, the area of the brainstem where the vestibular cranial nerve arises or further along the vestibular pathways.
Signs and Symptoms of Nystagmus
Nystagmus is associated with reduced vision, constant movement of the eyes which gets worse with tiredness or stress, fluctuations in visual acuity, sometimes with head nodding and often the head is carried at an angle and the eyes are kept to one side (this slows the movement, providing a null point and allows for better vision). Patients with nystagmus frequently have other vision problems such as astigmatism that require prescription eyeglasses and strabismus. Impairment to binocular vision is common with early onset nystagmus and depth perception is indirectly impaired in many patients.
The presence of a pale optic disk, or a history of progressive visual loss, should suggest that the nystagmus is acquired and possibly due to a neoplasm involving the visual system.
The following factors increase your chance of developing nystagmus: a family member with nystagmus, albinism, eye disorders such as optic nerve degeneration, severe astigmatism, or near sightedness, diseases of the body such as Menieres disease, multiple sclerosis, stroke, head injuries, use of medications, such as lithium or anti seizure medications, alcohol or drug use and infection of the inner ear.
Treatment for Nystagmus
At present there is no cure for nystagmus however, for the first time there are an increased number of researchers working on the condition and genetic research in particular offers new hope.
Contact Lenses Contact lenses have been shown to aid some nystagmus patients probably because of the actual contact with the eye leading to better control of the horizontal nystagmus movement.
Prisms can be used to help the eyes converge thus reducing the nystagmus.
Simple tests like visual acuity can be misleading as the vision may decrease if the patient is under stress or has latent nystagmus which causes an increase in nystagmus in both eyes when one eye is covered.
Biofeedback which teaches the patient to control eye movements to some extent by the use of visual and audio effects has been reported to be beneficial by some people.
Surgery, in particular tetonomy (cutting the eye muscles and reattaching them) has been quite successfully used in the United States. Botox, Baclofen and recently Mamentine and Gabapentin are drugs which are being tried out. There have been reports of good success with auricular acupuncture.
Living with Nystagmus
Nystagmus can affect nearly every aspect of life, including how a patient relates to other people, educational and work opportunities and self image.
Most people who have had nystagmus all their lives are not effected by the constantly moving image as their brain has adapted to the movement of the eyes, but those with acquired nystagmus can not adjust as well and may suffer from dizziness and vertigo.
Depth perception is usually reduced considerably, this can cause problems with balance and a perceived clumsiness.
Except for certain parts of the USA where optical devices are accepted, people with nystagmus can not get a driving licence so that they have to rely on public transport which can be a problem in itself in unfamiliar places.
Socially, because it is difficult for someone with nystagmus to maintain eye contact, it can be a problem maintaining self confidence. However there are many people with the condition who live an extremely successful and fruitful existence, adapting easily to their condition and building perfectly normal lives.
For children with nystagmus it is important that their teachers and classmates are advised as to how the condition affects them so as to prevent problems caused by misunderstandings. For example, children with nystagmus may read slowly because of the extra time needed to scan printed material. This should not be taken as a sign of poor reading ability. Students or school children with nystagmus may need extra time to study and when sitting exams. Many students with nystagmus use computers, as they can position screens to suit their own needs and adjust brightness, character size, and so on.