Infantile nystagmus. Development documented by eye movement recordings.

To report on the development of infantile nystagmus in a patient's first year of life. A case study using consecutive photo-oculographic and electro-oculographic eye movement recordings in the subject ranging between 1 and 12 months of age. Although no nystagmus was present at 5 weeks of age, square-wave jerks were recorded at 7 weeks, and a small pendular nystagmus was recorded at 8 weeks. At 10 weeks of age, evaluation revealed predominantly larger jerk-type nystagmus with increasing and decreasing exponential velocities of the slow phase. After 14 weeks of age, the nystagmus became smaller and was predominantly pendular. Between 7 and 12 months of age, binocular electro-oculography recordings showed conjugate pendular nystagmus typical of infantile nystagmus. This is the first report documenting that, at least in some forms of infantile nystagmus, eye movement abnormalities are not present at birth. Before the development of the typical pattern of infantile nystagmus waveforms (that is, conjugated pendular or jerk-type nystagmus with increasing exponential velocity slow phases), saccadic abnormalities (square-wave jerks) and jerk-type nystagmus with increasing as well as decreasing velocities were observed.