1、 Abnormal Stability Of Eyeball Fixation

Fixation stability refers to the good and stable fixation of the target of attention, which is very important to maintain binocular vision. Good and stable fixation is affected by macular integrity and regulation. Under normal circumstances, stable fixation can be maintained except for patients with very young age, excessive tension, ADHD and inability to concentrate. Poor fixation stability suggests lesions in the visual pathway, such as those in the macular region. There are also congenital nystagmus, recessive nystagmus, severe amblyopia and so on, which will cause the instability of eyeball fixation.

2、 Abnormal Saccade Movement

The rapid gaze movement that occurs when changing from one target to another is called saccade movement. Saccade movement can be produced actively or involuntarily in reading. Generally, the range of saccade movement will not exceed 20 degrees. During the saccade movement, vision is obscured until the end of the movement, which helps to maintain visual clarity. Abnormal saccade movement can observe the inaccuracy of movement. If the saccade movement exceeds the corresponding fixation target, it is called excessive movement, otherwise it is called insufficient movement. Factors such as infants or the elderly, fatigue, drugs or diseases of the central nervous system can also cause abnormal rapid saccade movement. There is a certain correlation between dyskinesia and normal saccade.

3、 Abnormal Eye Following Movement

Eye following movement can maintain continuous fixation with the macula. Poor eye following movement can indicate the existence of diseases, but it is more caused by eye functional reasons, such as amblyopia and esotropia in children, which can lead to abnormal eye functional following movement, such as misalignment and nystagmus.