What is amblyopia?

Amblyopia is a severe deterioration of visual acuity without a particular reason (i.e. diseases of the orbit, eye, optic nerve, or central nervous system). The vision in amblyopic is at least two orders of magnitude (in terms of examination by Snellen’s charts) worse than in the healthy eye.

We speak about amblyopia when the patient sees less than 60% in the best, optimal correction of vision defect with prescription lenses. Amblyopia can affect one or both eyes. If there is amblyopia of one eye, patients are not always aware of it.

It can develop during period of the most intense development of the visual apparatus – between 6 and 8 years of age. Its intensity, also called the degree of amblyopia, depends on the age in which it has developed. The younger the patient, the easier it is for amblyopia to develop.

Amblyopia may be caused by conditions such as:

• Unilateral strabismus.
• Anisometropia.
• Limited use of the eye – e.g. due to ptosis, corneal opacity, cataract, extensive covering of eye.
• Major refractive error, mostly hyperopia and astigmatism.

In unilateral strabismus (when only one eye is affected), amblyopia is a result of suppression of visual stimuli on the cortical level and loss of retinal fixation.

In anisometropia, when the difference in refractive error between the two eyes is larger than 2.5-3.0D, the quality of image perceived by each eye is so different that it cannot be correctly interpreted by the brain and binocular becomes impossible. The input of the eye with bigger refraction error becomes suppressed on the cortical level – this eye becomes the amblyopic eye. In some children, amblyopia may be caused by concomitant strabismus and anisometropia.

Amblyopia related to deprivation of stimuli is caused by the lack of stimuli, which are necessary for development of visual acuity and retinal fixation. Vision and fixation start to develop after birth – the process is triggered by special stimuli.

Severe, uncorrected hyperopia and astigmatism may cause binocular amblyopia due to the fact that images focused on the retina are blurred and of bad quality.

Amblyopia is one of the main causes of loss of visual acuity. Epidemiological data indicate that as much as 2% of the general population suffers from amblyopia.

Loss of visual acuity is the main symptom of amblyopia. There are three levels of severity:

• Severe amblyopia – when visual acuity drops below 0.1,
• Intermediate amblyopia – when visual acuity is between 0.1 and 0.3,
• Mild amblyopia - when visual acuity is between 0.3 and 0.8.

Ophthalmological examination conducted by a specialist or laser vision correction qualifying examination can determine the degree of amblyopia and its cause.
Amblyopia is curable only in children between 8 and 10 years of age. The effects of intervention will be greater if the patient is young and the degree is small. If the treatment is applied to late – full recovery may not be possible.

Regardless of its etiology, the degree of amblyopia can be determined after cycloplegia (application of mydriatic eye drops). In order to correct the refractive error, patient is prescribed with glasses, contact lenses or laser vision correction is recommended to him.

Treatment of strabismus-related amblyopia focuses on setting the eyes straight.
In amblyopia caused by anisometropia of over 3.0D, it is necessary to correct the refractive error by means of contact lenses or laser vision correction, which both reduce the difference in the size of the image perceived by both eyes.

Ophthalmologic examination conducted by a specialist or laser vison correction qualifying examination allow to determine the extent of amblyopia, its cause, as well as possible treatment outcomes. Set an appointment today via the CONTACT. 

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