DAROFF-DELLŐOSSO OCULAR MOTILITY
LABORATORY (DD_OMLAB)
LOUIS STOKES CLEVELAND DEPARTMENT OF VETERANS AFFAIRS MEDICAL CENTER
CASE
School of Medicine
10701 East Boulevard
Mail Code #151W
Cleveland,
OH 44106, USA
Phone: (216) 421-3224
Fax: (216) 231-3461
Website: http://www.omlab.org
Note: Information
from this page contains no medical advice.
You should always consult your doctor
about INS treatments.
This document was created by Z. I. Wang and edited by Dr. L.F. DellŐOsso.
Note: In this document, we have presented
very complex scientific information in laymenŐs terms.
DD_OMLAB
Patient Information Series:
1. INFANTILE NYSTAGMUS SYNDROME
v
What is Infantile
Nystagmus Syndrome (INS)? How common is INS in newborns?
Infantile
Nystagmus [nĭ-STAG-muss] Syndrome (INS) is characterized by the constant
movements of the eyes, even when you donŐt mean for them to. The eye movement
is usually horizontal (left and right). INS is also
known as congenital nystagmus. The incidence is reported to be about 1 in 3000
births (1 in 2000 males and 1 in 4000 females). We also see INS in dogs,
cats, goats and cows.
v
What caused INS?
INS
can appear when a baby is born, but is usually discovered a few months after.
INS is not directly caused by any sensory visual problems (for example, optic
nerve or retina problems), although it can happen together with these problems.
INS itself is caused by an unstable eye-movement
control system. Scientists have reported a gene (Xp11.4 – p11.3) to be
related to some forms of INS. INS can be a family disorder; the Ňnystagmus
geneÓ is usually carried from the mother to the son.
v
Do all the people
with INS have bad vision?
No.
INS by itself does not always reduce vision very much and many people with INS
lead normal, active lives. Those with very poor vision usually have other
sensory visual problems. These other problems are responsible for their
relatively bad vision.
v
Why do some INS
patients have a head turn? Why do some have head nodding?
A
consistent head turn indicates the patient can
see best at a certain angle. You can sometimes confirm the head turn by
checking old photos (especially photos that were not posed). If the head turn
is always in one direction, thatŐs an indication of a possible treatment to
improve INS. If you have a big head turn, you should consider surgery because
sometimes a big head turn or tilt may cause neck muscle problems. Surgery can
be done on the eyes so that you may see as well without turning your head.
The
nystagmus signal from the brain drives the eyes, it can also affect the neck
muscles. This causes the head nodding. Head nodding usually happens when you
are concentrating and trying really hard to see.
v
What should the
parents of children with INS do?
Parents
should bear in mind that INS will not prevent children from doing well in
school and becoming successful. Nothing is impossible with motivation and
support. This is not the end of the world. James Galway, the famous flautist,
also has INS. If your child has visual problems, make sure you let the teacher
know and ask the teacher to arrange a seat in the middle front row for your
child (a letter from your doctor may help).
v
What is Asymmetric
(a)Periodic Alternating Nystagmus (APAN)?
APAN
is one type of INS. It means the INS characteristics change with time. If you
have APAN, you may not have a preferred head turn position because your
nystagmus always changes. A large percentage of INS patients have APAN. The
tenotomy and reattachment (T&R) procedure can
help APAN patients see better over a wider
visual range.
v
What is Fusional
Maldevelopment Nystagmus Syndrome (FMNS)?
FMNS
is also known as latent/manifest latent nystagmus. It is usually noticed right
after birth. Latent nystagmus occurs when one eye is covered;
it beats in the direction of the open eye and disappears when both eyes
are open. Pure latent nystagmus is rare. Manifest latent nystagmus occurs when
both eyes are open; it beats in the direction of the
fixating eye (the eye you use to see). The waveforms of latent nystagmus
are different from those of INS. Right now there is no surgical treatment proven to be effective for FMNS. However, if a strabismus [stra-BIZZ-muss] procedure is
performed, T&R of the unoperated horizontal
muscles may reduce FMNS.
v
Why do people with
INS see worse when they are nervous?
INS
gets worse when you are nervous, angry or excited. When you are in an emotional
state, you will have increased nystagmus. INS is present whenever you attempt to
see, even in the dark. INS goes away when you are asleep or daydreaming.
v
Why canŐt I see my
eyes wiggling in the mirror, if I have INS? How can I see it?
You
canŐt see your eyes move, because the wiggling eye image in the mirror is
moving at the same speed as the image you see at the back of your eye (your
retina). To see your nystagmus, you should have someone videotape you.
v
With wiggling eyes,
why do most INS patients still see the world as being stable?
Since
INS happens at birth, the brain somehow knows early in life that the ŇdancingÓ
image on the retina is not a true image. The brain is clever enough to
eliminate the wiggling signal, and you can see the world as being stable.
However, it is normal that sometimes you see things jumping, especially when
you are tired, or when the object you are trying to see has a high contrast
against the background (for example, your digital clock in a dark room).
v
What is Acquired
Nystagmus (AN)?
AN happens later in life; it is a different type of
nystagmus from INS. AN can happen after accidents,
strokes or drugs. The major complaint from AN patients is that they see the
world as jumping around, because their brain cannot subtract the
movement of the eyes from the total visual information that it processes.