Related articles: Amblyopia
Definition
Amblyopia is a weakening of vision in one eye due to disuse in the course of visual and neuronal development *. In fact, to correctly process the visual input, the brain must receive a clear and correctly aligned image from each eye at the same time. When there is a persistent alteration of the image coming from one eye, but not the other, amblyopia can occur. In practice, the visual cortex suppresses the image perceived by the weaker eye (non-dominant).
The disorder, also known as "lazy eye", is the leading cause of monocular visual impairment (ie one-eye) among children. Amblyopia occurs, in fact, during the first years of life and, if it is not recognized and treated before 8 years of age, it can cause permanent loss of vision (* note: the development of visual pathways occurs mainly within the first 3 years of life, but is not complete until about 7-8 years of age).
Amblyopia can be caused by any condition that can disrupt normal visual development, including strabismus (misalignment of the eyes results in different retinal images) and the difference in refraction in the 2 eyes (for example, if one eye is more myopic, hypermetropic or astigmatic than the other focuses the images differently from those coming from the other eye). The lazy eye also occurs in the presence of other pathologies that affect the surface of the eye, the retina or any point of the visual pathways. Some examples are the congenital cataract (crystalline opacity present from birth) and the palpebral ptosis.
Most common symptoms and signs *
- Eye fatigue
- Learning difficulties
- Headache
- Nystagmus
- Misaligned eyes
- Reduced vision
- Double vision
- Blurred vision
Further indications
The main symptom of amblyopia is the reduction of visual acuity in the affected eye. Sometimes, the only obvious symptoms are related to a basic condition, such as strabismus, in which there is a deviation of the gaze. Other symptoms of amblyopia may include: involuntary movement of an eye, poor perception of depth, low sensitivity to contrast or movement. In some cases, it is possible to notice the problem as children squeeze or cover one eye.
If amblyopia persists long enough, vision loss can be permanent. Other possible consequences include problems in learning and development.
Diagnosis is based on the detection of a difference in visual acuity between the two eyes. A full eye exam is recommended for all children around 3 years.
The treatment of amblyopia depends on the cause and can include, for example, the prescription of glasses or contact lenses to correct the defect of refraction, or the removal of a cataract that prevents correct vision. The use of the amblyopic eye is encouraged by bandaging the part with the best functionality (dominant eye). Alternatively, atropine drops are instilled into the dominant eye, in order to stimulate the sight in the weaker eye.
