Nonstrabismic binocular vision abnormalities_ functional eye movement abnormalities

Nonstrabismic binocular vision abnormalities: functional eye movement abnormalities

The three most important components of eye movements are fixations, saccades, and regressions. The saccade movement generally accounts for 10% of the reading time, with 8~9 word spacing each saccade, about 2' viewing angle. There is a correlation between the time of the saccade and the distance of the required saccade. The saccade interval is the quiescence period, also known as fixation abort. The fixation interruption time in normal people is about 200-250 ms. Of course, there may be differences in saccade range and fixation time for different populations. The round-trip movement is a right-to-left movement, accounting for about 10%~200-/0 reading time. When the reader's target is inaccurate, misreads, or misunderstands the content of the article, there can be a round-trip movement. Eye movement defects can have a noticeable impact on reading. Functional ocular motor dys-function is a relatively common defect in visual skills, which is common in children with obvious reading difficulties, especially in children aged 5-13 years, because children in this age group have a high demand for reading and the symptoms are more obvious. Functional eye movement abnormalities mainly affect many of the patient's reading behaviors, such as following movements, saccade behavior, and fixation behavior, which affect both eyes. Symptoms are progressive. Functional ocular movement abnormalities must be distinguished from those caused by other organic lesions, which are often behaviors that affect the main forms of ocular movements, such as following movements or saccades, with abrupt onset and asymmetrical behavioral features. Many children with functional eye movement abnormalities come to the clinic primarily because of problems with visual tracking, which may also have problems with binocular vision and accommodation. Many of the symptoms of symptomatic patients are closely related to reading, and the common symptoms are as follows. 1. Poor positioning function. 2. Read certain lines of font frequently and repeatedly. 3. Excessive head movement while reading. 4. There are word skips and sentences when reading. 5. Difficulty transcribing from a white writing board to paper. 6. It is easy to make mistakes when filling in some letters that are relatively close. 7. Miscoordination between the eyes and the head. 2. Signs 1. Fixation is poor during the occlusion test. 2. Unstable gaze and lack of concentration. 3. There can be some behavioral anomalies. 4. For example, in some tests that objectively observe eye movements, the behavior is lower than normal. III. Diagnosis 1. Take a history to find out the patient's age, reading habits, whether symptoms are related to these functional causes, severity (whether they interfere with close reading and work), triggers at the time of symptoms, accompanying symptoms, alleviating factors, and whether there are some neurologic symptoms. 2. General ocular examination and refractive examination If the patient has uncorrected refractive error, refractive correction should be performed first, and then binocular vision function test will be performed on the basis of refractive correction. 3. Measurement of near binocular visual function includes occlusion test, near horizontal heterogiosis measurement, convergence near point measurement, AC/A, fusion convergence and dispersion range, adjustment flexibility, adjustment amplitude measurement, convergence and dispersion flexibility measurement, etc. These findings can help in the differential diagnosis and in determining whether there are abnormalities in aggregation and accommodation. 4. Stereopsis Measurement of stereopsis is also required, as a decrease or absence of stereopsis often indicates the presence of strabismus. 5. Cycloplegic dilated refraction can rule out latent refractive errors. 4. Differential diagnosis 1. Uncorrected refractive error Farsightedness, myopia, astigmatism, especially anisometropia in both eyes, will affect the effectiveness of binocular visual function. 2. Strabismus Patients with strabismus can also experience symptoms similar to functional eye movement abnormalities, and strabismus itself can also cause some symptoms associated with functional eye movement abnormalities, a phenomenon that is common in alternating and intermittent strabismus, possibly due to fixation instability or poor fixation function. 3. Convergence or accommodative dysfunction Such patients will also have symptoms similar to functional eye movement abnormalities, which can be distinguished by a detailed binocular visual function examination. 4. Drug factors Some drugs can affect eye movements, such as some antidepressant drugs, so the patient's drug history should be understood and identified. 5. Handling principle 1. Additional lenses such as attaching low-power positive lenses. 2. Visual training is mainly fixation training, such as spatial saccade motor training.。