CONGENITAL NYSTAGMUS

What is it?

Congenital nystagmus (CN) is an inappropriate "wobble" of the eyes. Typically it begins in the first year of life as a fairly smooth type of wobble and then in the second year of life becomes a jerky type of wobble.

Causes

No one really knows why CN happens. In some patients there is a very strong family history. Poor visual development in the first weeks of life may cause CN. A subtle abnormality in the way the muscle attaches to the eyeball has been seen in some patients with CN.

Special Tests

Eye movement recordings and retinal function tests (ERG) are sometimes required to sort out what is happening to one particular patient's nystagmus. The results of these tests can help suggest what the future holds for this patient and sometimes can suggest some therapy.

Associations

Many patients who have CN also have one or more of the following problems:
1. Refractive error. This is a focussing error that requires glasses (or contact lenses). Some patients with a CN have quite weird refractive error and require quite strong glasses to focus clearly. Contact lenses may give better vision than glasses.
2. Sensory disorders. Some patients with CN have defects of some of the cells of retina that means that visual development was never going to be excellent. Albinism is the commonest sensory defect that is associated with CN.There is adetailed Handout on albinism here.
3. Strabismus/amblyopia. About one third of patients with CN also have strabismus (turned eye) or amblyopia (lazy eye). Treatment of strabismus and amblyopia is more difficult in patients who have CN.

Effects

The two commonest effects of CN are:
1. Face turn. The patient subconsciously finds that in one position of the head the vision is clearer. When the patient is older they tend to frequently adopt this abnormal head posture for watching TV, reading, etc. If this abnormal position usually looks weird then surgery can be offered to the eye muscles that usually straightens the head quite effectively.
2. Blur. This can be due to the refractive error, the sensory defect (such as Albinism) or may be due to the wobble itself. Wobbly eyes may not see as clearly as normal still eyes. Surgery to the eye muscles can sometimes lessen the blur that these patients experience.

Treatments

Treatment can involve one or more corrective spectacles, contact lenses, drugs and eye muscle surgery. Further details about drugs and eye muscle surgery are available on other Handouts from The Private Eye Clinic.

For Internet surfers:

www.btinternet.com/~lynest/nystag01.htm
http://www.nystagmusnet.au