Nystagmus is when the eyes oscillate. This movement can be either side-to-side, up-down, or in a rotary motion. Nystagmus is a normal thing after a person has been spun in circles, but not when the person has just turned their head to the side or is sitting still. There are different reasons behind an atypical nystagmus (meaning not after being spun), but the most common reason I see it in children is when they have neurological damage. Here is a link that explains it well:
Because the eyes are oscillating, often the children complain of things looking blurry when they look straight ahead. Since there is not a cure for it, children should be allowed to adapt in order to perform activities to the front of them such as reading and writing. The most common adaptation is the child tilting their head and looking out of the corner of their eyes. Now, this may be something we wouldn't want a child to do if they have other diagnoses such as hemiplegia/hemiparesis with hemianopsia or other one-sided problems. In those cases we would want to encourage the child to look to the middle of their body with the paper or book placed to the center of them. Just be aware that forcing a child with nystagmus to look straight ahead to perform table-top activities could give them headaches and cause them to be distractible....if everything I tried to focus on was blurry, I would lose focus quickly too! Fidgeting and grouchiness will soon follow the distractibility if forced to keep looking to the center. This is especially hard when dealing with toddlers and preschoolers because sometimes they lack the words to express that things look blurry, whereas older children can often tell us their symptoms.
Another accommodation could be to angle the papers that they are reading or writing on. Anywhere from a 30-90 degree angle could be appropriate. An example of writing on a 90 degree angle would be to draw on paper taped to the refrigerator. An example of a 30 degree angle would be taping or clamping paper on to a 3-ring binder that is declined, with the rings perpendicular to the child. Angles in between those could be achieved on a desk or standing easel.
When dealing with puzzles, artwork, or other fine motor activities it may also be appropriate for the child to be allowed to stand up to do the task and not be forced to stay seated. So often in daycares or Mother's Day Out programs I see that the little children are being taught to stay in their chair, but this may not be appropriate for a child with a nystagmus problem.
If the child with nystagmus is young and the pediatrician is not aware of it, be sure and share this information with them. Maybe a referral to a developmental optometrist, opthalmologist, or neurologist will be needed. If the child is older and hasn't been to an eye doctor lately, a referral to either the developmental optometrist or opthalmologist may be needed. Many developmental optometrists will write up reports full of functional information that can be shared with the daycares/schools and placed within an IEP.