Nystagmus is the word used to describe an involuntary movement of the eyes. It is characterized by a slow, sweeping movement in one direction, followed by the eye snapping back quickly in the other direction. It most often includes both eyes, and can be exaggerated when the person moves his eyes to look in a certain direction. The presence of the nystagmus condition can be benign and harmless, or it can be an indication of a pathology, or an underlying problem. There are many classifications of nystagmus, depending on the reason for its presence as well as the time of life in which it becomes apparent.
Some types of nystagmus are actually considered normal. For example, when a person looks far toward one direction, a minor twitching of the eye muscles to bring the eye back toward the center is not uncommon or a cause for concern. Most other varieties result either from disease, trauma, or neurological disorders.
Congenital nystagmus is present at birth, and is usually discovered when the child is at a very young age. In this case, it is usually called manifest nystagmus if it is present at all times, or latent nystagmus if it happens only when one eye is covered. There is also manifest-latent nystagmus, somewhat of a combination of the two, where it is always present to some degree, but worsens when one eye is covered. In some cases, it presents as an isolated issue, and is not connected with any other problems.
If the condition is not present at birth, but is brought on by some event later in life, it is referred to as acquired nystagmus. In this case, there is most often some type of neurological problem at the root of it. Some of the many conditions which may cause nystagmus are multiple sclerosis, brain tumors, and Wernicke's encephalopathy. The abuse of harmful or controlled substances such as phencyclidine (PCP), lysergic acid diethylamide (LSD), barbiturates, lithium, and anti-depressants can also bring it on.
Traditionally, it has been thought that congenital nystagmus could not be treated, but some drugs developed in recent years have shown some potential for treating it. Other treatments that do not involve drugs have worked for some who suffer from it, and these include contact lenses, low vision rehabilitation, and certain surgical treatments. No single treatment has been found to be a comprehensive cure, but more drugs and surgical corrective techniques continue to be developed.