The visual impairment known as “nystagmus” is characterized by involuntary rhythmic shaking or wobbling of the eyes and has often been described as “dancing eyes” or “jerking eyes.” The eye movements indicative of nystagmus may be back and forth like a pendulum, or the eyes may move slowly in one direction and then quickly in another direction. The eyes may move laterally or vertically and at different speeds. There are over 45 different types of nystagmus; however, there are two that are most common. Early onset nystagmus begins very early in life and is often associated with vision loss while acquired nystagmus occurs later in life.
Early onset nystagmus often accompanies loss of vision at birth or soon after birth. Nystagmus is one of the first indicators that a child is suffering from vision loss. According to statistics, one in every 1,000 children has nystagmus; in 80-90% of these cases, this visual impairment is a side effect of vision loss from an eye disease such as albinism, aniridia, congential cataracts, or retinopathy of prematurity. Early onset nystagmus is often seen around the sixth to eighth week of life.
The most common nystagmus related to vision loss during childhood is called “pendular nystagmus,” which is characterized by the eyes rotating back and forth like a pendulum. Children with early onset nystagmus do not notice movement of their vision as their eyes shake. Nystagmus does not typically worsen over time; in fact, improvement is often seen by adulthood. Though not all cases of early onset nystagmus are genetic, most cases are associated with inherited ocular diseases. Genetic counseling can help determine if you are capable of passing this condition onto your children.
Acquired nystagmus may manifest later in life due to neurological dysfunction such as a traumatic brain injury, multiple sclerosis, or brain tumors. Patients with late onset nystagmus, unlike those with early onset, do notice movement in their vision related to the nystagmus movements (this is called “oscillopsia”).
Late onset nystagmus is more likely to be directional in nature with the eye moving slowly in one direction, then moving quickly back. The nystagmus may change as the person looks in different directions. Because unexplained onset of nystagmus in an adult may indicate a serious neurological problem, an examination is necessary immediately following the discovery of nystagmus.
As with amblyopia and strabismus, treatment for nystagmus will vary from patient to patient. Contact lenses and eyeglasses have been show to aid some nystagmus patients. With contact lenses, a theory that the tactile feedback of feeling the lenses on the eyes leads to better control of the movement of the eyes has been examined. Contact lenses also move with the eye and provide better image quality.
BOTOX® has actually been used to paralyze ocular muscles, thus reducing nystagmus. Since BOTOX® lasts only a short period of time, this treatment is not considered practical; also, general anesthesia is required, so the injection can be made into the ocular muscles. Baclofen (muscle relaxant and antispastic drug) and biofeedback have been used successfully to treat nystagmus, also.
If you would like to learn more about nystagmus or have your child tested for this visual impairment, please contact an eye doctor in your area today.