Deprivation amblyopia

Introduction Amblyopia refers to normal eyeball examination and abnormal eyesight in one eye or both eyes, and can not reach 0.8 or above by wearing glasses. According to different types, medical amblyopia is divided into strabismic amblyopia, hemiplegic amblyopia, and form deprivation. There are five categories of amblyopia, ametropic amblyopia, and congenital amblyopia. Form deprivation amblyopia: In infants and young children, due to corneal opacity, congenital cataract, or ptosis to block the pupil, the light stimulation can not fully enter the eye, depriving the macula of the opportunity to receive normal light stimulation, resulting in functional disorders amblyopia.

Cause

Visual deprivation amblyopia is often caused by congenital or early acquired factors that cause visual stimuli to decrease. In infants and young children, due to ocular opacity (such as cataracts, corneal scars, etc.), completeness The ptosis, inappropriate eye mask covering the eyes, etc., limit the full input of perceptual perception, interfere with the normal development of vision, and all produce amblyopia. For example, the right eye is a cataract, and external objects cannot be clearly imaged on the retina, only partially diffuse. Light enters the eye, and the effective stimulation of the retina is insufficient, resulting in low vision in the right eye. Form deprivation amblyopia is the most serious and the least visible form of amblyopia.

an examination

Related inspection

Vision screening retinoscopy retinoscopy corneal vision

Physical and laboratory tests:

1. Young children may not have any symptoms. Older children may complain of poor eyesight. Parents may find some abnormal visual behaviors, such as blinking, head tilt, and prefer to place objects when they are close to objects. Waiting at a glance.

2. Patients may have congenital cataract, corneal scar, etc., congenital ptosis and so on.

3. Low vision and no correction. Since most patients with amblyopia are children, it is important to choose the appropriate visual assessment method.

4. Light perception changes. The visual acuity of the medium-density light sheet placed in front of the amblyopia is not lowered, and the visual acuity is decreased in the presence of organic lesions. In dim and faint light, the visual acuity of the amblyopic eye does not change much.

5. Crowding occurs. The ability to recognize a single font is much higher than that of a font that is the same size but lined up.

6. Stereoscopic vision drops or disappears.

7. The amplitude of the adjustment of the amblyopic eye decreases.

8. Accompanied by exotropia, nystagmus, etc.

9. The contrast sensitivity function of the amblyopic eye decreases at medium and high spatial frequencies with a peak left shift.

10. There are two types of gaze in the amblyopic eye, namely, central gaze and eccentric gaze. The gaze is gazing at a point other than the fovea, and is sub-centered. Look around the macula and around.

11. Children with amblyopia showed a decrease in amplitude of visual cortical evoked potential (VEP) and prolongation of peak time. This change in the amblyopic eye is more pronounced at high frequencies.

Differential diagnosis

Strabismus amblyopia: The patient has strabismus or has had strabismus, accompanied by amblyopia, but no fundus abnormalities. It is currently believed that this is because strabismus causes diplopia and visual disturbances to make the patient feel extremely uncomfortable. The visual cortex of the brain actively suppresses the visual impulse of the afferent macula by the oblique eye. The macular function of the eye is inhibited for a long time, forming amblyopia. This amblyopia is a consequence of strabismus, secondary and functional, and thus reversible, and the prognosis is good. However, occasionally a small number of primary subjects are not significantly improved even under active treatment.

Anisometropic amblyopia: due to the inconsistency of the image formation formed by the macula in both eyes, even if the refractive error is corrected, the object size caused by anisometropia is still different, which makes the eyes of the eyes difficult or impossible to merge into one. The cortical center can only suppress the phenomenon of refractive errors and larger eyes, and it is a long-term amblyopia. This kind of amblyopia is also functional and thus reversible.

Congenital amblyopia: the pathogenesis is not yet fully understood. VonNoorden speculated that neonates often have retinal or visual pathway bleeding, which may affect the normal development of visual function. Some congenital amblyopia is secondary to nystagmus.

Refractive amblyopia: mostly bilateral, occurring in patients with high refractive errors who have not worn corrective glasses. The binocular vision is equal or similar. Refractive amblyopia is more common in hyperopic refractive errors. This kind of amblyopia is similar to the binocular vision. There is no fusion disorder between the two eyes, so it does not cause the macular function to be inhibited. Therefore, after wearing appropriate corrective glasses, the visual self-energy can be gradually improved without special treatment, but it is longer.

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