What is Amblyopia?

During the visual development period, the best corrected visual acuity in one or both eyes due to abnormal visual experience such as monocular strabismus, refractive error, high refractive error, and shape deprivation is lower than normal children of the corresponding age, and there are no organic lesions in the eye examination. Called amblyopia. Lower limit of normal vision for children of different ages: The lower limit of normal vision for children aged 3 to 5 years is 0.5, and the lower limit of normal vision for children 6 years and older is 0.7. Amblyopia is an eye disease that seriously endangers children's visual function. If left untreated, it can cause amblyopia and even blindness.

Basic Information

English name: amblyopia
Visiting department: Ophthalmology

Multiple groups: Toddler
Common causes: Strabismus, refractive error, or refractive interstitial opacity
Common symptoms: Vision and refractive errors, dyslexia, eye movement disorders, etc.

Causes of Amblyopia

Strabismic amblyopia

Occurs in monocular, children with or have had strabismus, common in children with monocular constant strabismus that develops under four years of age, because the cerebral cortex actively inhibits the visual impulse of strabismus and inhibits the formation of amblyopia for a long time. The difference is generally that the suppression can be released when the squint eye is injected, while the amblyopia is continuous vision loss. The earlier the age at which strabismus occurs, the faster the suppression occurs and the deeper the degree of amblyopia.

2. Ametropic amblyopia

Due to the different vision of the two eyes, the size of the retinal imaging of the two eyes is different, and the macular part of the eye with a higher refractive power is large and blurred, which causes insufficient fusion reflex stimulation of the two eyes, which can not form binocular single vision, which results in passive suppression and two eyes flexed. If the light phase is more than 300 degrees, amblyopia and strabismus are often formed with high refractive power. As a result, passive and active suppression coexist. The depth of amblyopia is not necessarily related to the degree of refractive error, but it is related to the nature of fixation. The degree of amblyopia is deeper in the side-center gaze. The nature of this type of amblyopia is similar to strabismic amblyopia and is functional and reversible. Sometimes it is not easy to distinguish whether amblyopia is caused by ametropia or secondary to strabismus. If this type can be detected early, wearing glasses can prevent it.

3. Ametropia

Most of them are binocular and occur in children or adults with high myopia, myopia, and astigmatism without corrective glasses. Most of myopia is above 600 degrees, hyperopia is above 500 degrees, astigmatism 200 degrees, or both. Binocular vision is equal or similar, and there is no functional impairment of binocular object image fusion, so it does not cause macular functional suppression. If you wear appropriate glasses in time, vision can gradually improve.

4. Disuse amblyopia (form deprivation amblyopia)

In infancy, due to ptosis of the upper eyelid, cloudy cornea, congenital cataracts, or because the covering time after eyelid surgery is too long, light stimulation cannot enter the eyeball, which prevents or blocks the macula from receiving shape stimulus, thus causing amblyopia. Also known as blocking visual irritation amblyopia.

5. Congenital Amblyopia or Organic Amblyopia

Due to macular hemorrhage at birth, the arrangement of cone cells is irregular, which occurs before the baby's eyes are formed after birth, so the prognosis is poor. Although some retinal and central nervous systems cannot detect obvious lesions, they are still considered to be organic lesions. Due to the current examination methods, this type is constant amblyopia, and the treatment is ineffective.

Amblyopia clinical manifestations

Vision and refractive abnormalities

The visual acuity boundary between amblyopic eyes and normal eyes is not very clear. Some patients complain that their vision has decreased, but the objective vision is still 1.0 or 1.2. This may be a result of the patient's vision loss compared to their previous vision. In addition, there may be some obstacles in the visual cells in the central fossa or the conduction system behind them, there are very small dark spots in the center, and there are conscious visual impairments that cannot be objectively detected.

If the amblyopic eye has no organic changes, and its visual acuity is above 0.01 and below 0.2, it is often accompanied by fixation abnormalities.

The relationship between amblyopia and refractive error, farsighted eyes account for a large proportion, and myopia has more mild amblyopia, so amblyopia is closely related to those with high hyperopia.

Severe amblyopia is more common in esotropia than exotropia, which may be due to the onset of esotropia earlier than exotropia.

2. Difficulties in reading

Or crowding. When using the same optotype, illuminance and distance to check vision, the distance between optotypes is different, and the measured values are different. Dyslexia is a feature of amblyopia.

Difficulty of reading is that the ability of amblyopic eyes to recognize individual optotypes is better than to identify sets or dense optotypes. That is, the resolution of single fonts (such as E) on the visual chart is better than that of lines of characters.

3. Amblyopia only occurs in young children

Binocular amblyopia develops gradually from birth to 9 years of age. Amblyopia can result from strabismus or loss of form during this development period. After 9 years of age, amblyopia does not occur even for the above reasons.

4. Amblyopia only occurs in monocular patients

Amblyopia does not occur if two eyes are used alternately.

5. Abnormal fixation

People with deep amblyopia often have macular fixation instead of the macula due to poor macular fixation. Eccentric fixation refers to fixation outside the fossa fossa. There are many doctrines, but its manifestations include concavity fixation, peripheral fixation, fixation near the macula, and walking fixation.

Amblyopia

1. Visual inspection.

2. External eye and fundus examination.

3. Refractive examination.

4. Squint inspection.

5. Fixation inspection.

6. Binocular monocular examination.

7. Retinal correspondence check.

8. Fusion function check.

9. Stereo vision inspection.

Amblyopia Differential Diagnosis

It needs to be distinguished from similar symptoms caused by refractive errors, strabismus, myopia, and other eye diseases.

Amblyopia treatment

Eliminate inhibition, improve vision, correct eye position, and train macular fixation and fusion functions to restore binocular vision. The treatment effect of amblyopia is related to age and fixation. It is better at 5 to 6 years old, and worse at 8 years old; central fixation is better, and lateral fixation is poor.