I noticed that my baby’s eyes are wobbly. What do you call this condition? Will this disappear as he grows older?
The term nystagmus is used to describe an involuntary rhythmic movement or oscillations of the eye. These movements can be characterized as either pendular or jerky. The pendular type is present when the movements have equal velocity in each direction. On the other hand, jerk nystagmus is present when a fast eye movement is seen in one direction and a slow movement in the opposite direction. Nystagmus may also be characterized as horizontal, vertical or rotatory. In most cases there is a position of gaze where the nystagmus diminishes and this is referred to as the null point. Patients with nystagmus often adopt a compensatory face turn to maintain the eyes at the null point, thereby improving visual acuity. Patients with nystagmus should be referred to an ophthalmologist for a full eye evaluation.
It is helpful to classify nystagmus as either congenital or acquired. It is important to recognize acquired nystagmus, as it may be a sign of significant central nervous system disease.
As the name implies, the onset of congenital nystagmus is early, usually by 6-8 weeks of life.
Because of this early onset, the brain is able to suppress the motion. Therefore these babies do not perceive oscillopsia or the cyclic motion associated with nystagmus. There are 2 basic subtypes of congenital nystagmus: congenital motor, and sensory.
Congenital motor nystagmus is usually presents in both eyes and symmetric. It occurs during the first month of life and is often inherited as an x-linked trait. The compensatory face turn used to minimize the nystagmus is usually established by 2-4 months of age. These children have relatively good visual potential (usually around 20/50 or better), particularly when face turning is used by the patient. However, face turning produces physical as well as social discomfort. Is there something that can be done about the face turn? There are several surgical procedures that can be done to move the attachments of the eye muscles to shift the null point to primary gaze. However, the long term results of this surgery is variable, as many patients readopt the abnormal head posture after surgery.
Sensory nystagmus is due to the lack of the fixation reflex secondary to neonatal blindness. Any disease that results in bilateral neonatal blindness such as congenital cataracts, corneal opacities, congenital optic nerve atrophy or hypoplasia, and congenital retinal disorders, can cause this form of congenital nystagmus. The pattern of sensory nystagmus is usually indistinguishable from congenital motor nystagmus, except that the nystagmus has a larger amplitude and the movements show poor fixation with a searching character. The onset is later than congenital motor, usually occurring after 6-8 weeks of life. Patients with sensory nystagmus rarely adopt a compensatory face turn.
Nystagmus acquired in infancy, may be a sign of a serious neurological condition, and therefore warrants a neurology consult. Neurologic disease involving the any part of the brain can cause nystagmus. In contrast to congenital, acquired nystagmus is often associated with the perception of the environment moving, or oscillopsia. Oscillopsia, therefore, is an important indication that the nystagmus is acquired. Only patients with acquired nystagmus will experience oscillopsia; as these patients do not have the plasticity to suppress the shaking image.