The Dr. Bill Takeshita Foundation

Last Modified: Sat, 18 Aug 2007

View other Common Causes of Vision Impairment

Nystagmus is the term that describes the uncontrollable shaking of the eyes. It can occur in healthy eyes as well as in the eyes of children born with congenital eye pathology such as albinism, cataracts, glaucoma, Aniridia, optic nerve hypoplasia, and retinopathy of Prematurity. Patients with nystagmus may have 20/20 sight or sight as poor as 20/400. It is sometimes an inherited trait that affects males and females equally. In many cases, nystagmus will improve with age but it rarely is completely eliminated with treatment.

Nystagmus is generally described based on the direction of the eye movements. Horizontal nystagmus is the most common form of nystagmus where the eyes move uncontrollably in a horizontal manner. Horizontal nystagmus often consists of a fast phase where the eyes move quickly towards one direction and slowly in the other direction. Consequently, horizontal nystagmus is also called jerk nystagmus because the eyes jerk quickly in one direction. Pendular nystagmus describes the condition where the eyes move back and forth similar to a pendulum of a grandfather clock. Vertical nystagmus describes nystagmus where the eyes move up and down vertically. In all forms of nystagmus, the speed and degree of nystagmus generally correlates with the degree of vision. Patients with rapid nystagmus tend to have better vision as compared to those with slow moving nystagmus. Similarly, patients who have a low degree of movement tend to have better sight than those with large degrees of movement.

Patients with nystagmus frequently turn or tilt their head to position their eyes to minimize the nystagmus. For many patients, nystagmus will reduce when the eyes are positioned in a particular field of gaze. This is called the null point. The null point tends to differ for each person. The use of prismatic spectacles and eye muscle surgery are sometimes used to position the eyes in the null point to reduce or eliminate the head turn or tilt that sometimes co-exists with nystagmus.

Patients with congenital nystagmus generally do not perceive the world as moving or shaking. However, adults who acquire nystagmus secondary to stroke, cerebral vascular accidents or trauma typically are bothered by the shaking or movement of the images that they see. Consequently, many adults with acquired nystagmus keep their eyes closed and don’t use their vision as an attempt to minimize the dizziness and nausea they experience due to the moving images.

There is no treatment that completely eliminates or cures nystagmus. Nystagmus that is present among young infants often improves with time. The use of corrective glasses, vision therapy, rigid contact lenses, and eye muscle surgery can reduce nystagmus. There are some cases of nystagmus in which the nystagmus is only present when one eye is covered. This is called latent nystagmus and can be prevented by not winking, closing, or covering one eye. For these children, it is important to keep their hair away from their eyes and to position them such that they have an unobstructed view of the chalkboard with both eyes. Nystagmus can increase among patients when they are tired, nervous, or when they look towards their extreme right and left fields of gaze.

Recommendations

• Infants with nystagmus must be evaluated by a pediatric ophthalmologist to rule out potential neurological problems.
• An eye examination by a developmental optometrist can provide spectacles, prisms, and vision therapy activities to attempt to reduce nystagmus.
• Patients with blurred sight due to nystagmus will benefit from a consultation by a low vision specialist and low vision aids. Bioptic spectacles, specialized reading glasses, wide-angle magnifiers, and closed circuit televisions can be very helpful.
• Students should be provided with additional time for reading, writing, and copying from the chalkboard. Nystagmus can interfere with the efficiency of moving the eyes in a left to right reading pattern.
• Students with vertical or Pendular nystagmus will benefit from using wide bold lined paper to help them to maintain their place when writing.
• Thick pencils, bold markers, and 1.0 mm gel pens are easier for students to read their writing if they have nystagmus and blurred sight.
• Students with blurred sight will benefit from having access to handouts and other materials that are normally presented on the board.
• The use of bold architecture chalk and bold dry erase markers with black ink will help students with nystagmus and blurred sight to access written material on the board.
• The use of large print text books can be very helpful to assist students who have difficulty tracking letters and words when reading.
• Modifications to the computer screen to enlarge the font size and spacing are very helpful. For instructions, please see Solutions to Help You Use the Computer.
• Specialized software programs are available that will modify the size of the fonts and spacing between letters to make reading easier for students with moderate to severe nystagmus. For more details, see Computer and Assistive Technology.
• The following low vision aids have been helpful for patients with nystagmus and blurred sight
  • Scanning CCTV called My Reader. This can scan and reformat the text to display only one word or one line of text on the screen at one time.
  • The J Bliss VIP scanning software program scans and modifies the text size and spacing for easy reading.
  • Binocular aspheric reading spectacles provide a wide field of view to assist with reading.
  • Vision therapy saccadic tracing activities can improve the efficiency of tracking eye movement skills.
  • The use of a typoscope or plastic window cutout to display only one line of text on the page at a time can be very helpful.
• For more information, please see Low Vision Rehabilitation