What is nystagmus?
Nystagmus is characterised by a rapid involuntary movement of the eyes, usually from side to side. The eye movement is not necessarily in a horizontal plane – it could be a vertical or circular movement.
The majority of those with nystagmus have vision which is significantly worse than average and well below what is considered to be short sighted. In the UK, many people with nystagmus are eligible to be registered as partially sighted and a small number meet the criteria to be registered as blind.
Nystagmus is not contagious or infectious. Nystagmus is not painful and does not lead to total blindness. Vision seems to improve until it stabilises around the age of five or six.
How common is nystagmus?
Nystagmus affects around 1 in 1,000 people.
Prevalence figures can vary widely because different studies might exclude certain types of nystagmus, for instance, they might exclude people with acquired nystagmus.
What types of nystagmus are there?
A number of keywords can be used to describe the type of nystagmus that someone has. These keywords include:
Acquired — meaning that at one stage, the person did not have nystagmus but they do now, i.e. they acquired it. Nystagmus can be a secondary condition to other medical conditions like Multiple Sclerosis.
Congenital — meaning born with the condition. Note that there is no evidence that people are actually born with nystagmus as it is not usually identified until weeks or months after birth. For this reason, infantile is often used instead.
Idiopathic — meaning no known cause. We know that nystagmus can be hereditary or associated with Albinism. If thorough tests cannot make a link with any known causes, then the nystagmus can be described as idiopathic.
Infantile — meaning that nystagmus was identified in early childhood. Nystagmus is generally identified within the first 6 months after birth.
These adjectives can be put together to describe the type of nystagmus. In my case, I was diagnosed with it within the first 6 months of birth and tests carried out in the UK by one of the leading nystagmus research units could not identify a cause. I have infantile idiopathic nystagmus.