Amblyopia and it’s management

Tukezban Huseynova, MD

Specialist in Strabismus and Refractive Cornea,Briz-L Eye Clinic, Baku, Azerbaijan

Tukezban@gmail.com

Amblyopia is derived from Greek and means “dullness of vision.”

Amblyopia is a condition of diminished visual form sense which is not a result of any clinically demonstrable anomaly of the visual pathway and which is not relieved by the elimination of any defect which constitutes a dioptric obstacle to the formation of the foveal image.

Classification Stimulus deprivation amblyopia: this may be unilateral or bilateral and may be

- complete, where no light enters the eye - partial, where there is some passage of light into the eye.

Strabismic amblyopia: which is the result of manifest strabismus and is caused by constant unilateral strabismus in childhood.

Classification Anisometropic amblyopia: significant difference in the refractive errors of the two eyes where one eye has the visual advantage at all distances.

Meridional amblyopia: is the result of uncorrected astigmatism where one or both eyes are predominantly astigmatic.

Ametropic amblyopia: is the result of a high degree of uncorrected bilateral refractive error.

Occlusion amblyopia: occur after use of total occlusion or atropine, particularly before the age of two years. Visual acuity is usually restored with careful treatment and monitoring.

AetiologyAmblyopia may be unilateral or bilateral and the cause may be any or a combination of the following factors.

Light deprivation. There is no stimulus to the retina.

Form deprivation. The retina receives a defocused image as with refractive errors.

Abnormal binocular interaction. Non-fusible images fall on each fovea, as with strabismus.

Eye movements in Amblyopia.

- The amblyopic eye made irregular, jerky movements

- A delay in information processing by amblyopic eyes was thought to be the cause of increased saccadic movement

Visual Deprivation Amblyopia.

Visual deprivation is caused by occlusion of the visual axis.

No view

Features

- Visual-deprivation amblyopia (VDA) can be unilateral or bilateral.

- Sensory strabismus often occurs in children with unilateral vision deprivation.

What causes VDA? Congenital Cataracts,

Ptosis,

Congenital Corneal opacities,

Vitreous hemorrhage

Temporary hyphema, or

Temporary eyelid edema in a very young child 

Amblyopia is more likely to occur, be more severe, and be more resistant to treatment when the defect is UNILATERAL.

Strabismic Amblyopia.

Is always unilateral.

More often in esotropes than in exotropes.

Assesment of fixation preference

Amblyopia exists monocular or binocular

Clinical features of Strabismic Amblyopia

Clinical features of Strabismic Amblyopia

Fixation Preference The assessment of fixation preference is used mostly as a more practical

test for visual acuity differences between the two eyes. 

Clinical features of Strabismic Amblyopia

Visual AcuityWhat degree of reduction in visual acuity

of one eye should be designated as amblyopia? ??

- A difference of two lines on a visual acuity chart is commonly used as a diagnostic criterion of amblyopia.

- Every difference in visual acuity produced by amblyopiogenic factors should be classified as an amblyopia.

Clinical features of Strabismic Amblyopia

Strong fixation preference in a strabismic infant. 

A, A child with right esotropia may not object to having the deviated eye covered but protests occlusion of the dominant left eye. 

B, In this patient amblyopia of OD must be suspected

Clinical features of Strabismic Amblyopia

Fixation pattern of the amblyopic eye.

Bangerter’s classification

1. Central fixation

2. Eccentric fixation ( nonfoveolar: parafoveolar and parafoveal)

3. No fixation

Anisometropic Amblyopia

Anisometropic amblyopia may occur in children with hyperopia, myopia, or

astigmatism.

Anisohyperopia as small as 1.0 D,

Anisomyopia as small as 2 D, or

Anisoastigmatism as small as 1.5 D

produce

Amblyopia.

The mechanism responsible for the development of amblyopia in patients with anisometropia is

thought to be similar to that which occurs in those with strabismic amblyopia.

Examination of the Patient with Amblyopia.

Vision assessment techniques vary depending on the age and abilities of the individual child. In preliterate children, techniques that assess visual behavior are utilized, whereas in older and literate children, psychophysical (quantitative) recognition testing of visual acuity is usually possible.

Management of Amblyopia.

The goal of amblyopia treatment is to achieve the maximum visual acuity and visual function possible for an individual patient.

Elimination of factors obstructing the visual axis, such as cataracts and ptosis, is critical for patients with deprivational amblyopia.

Other steps include correction of significant refractive errors, and encouraging use and development of vision in the amblyopic eye through occlusion therapy, penalization, or both. These steps are outlined below. 

Optical CorrectionCorrection of significant refractive errors is important to

ensure that a clear image is focused onto the fovea of each eye.

Occlusion TherapyOcclusion is typically accomplished by placement of an

adhesive patch directly over the sound eye or use of a patch that fits over the spectacle lens.

Occlusion Therapy

Patching Regimen

  The daily duration of recommended occlusion remains controversial.

Amblyopia can be effectively treated with prescribed patching regimens much less than the full-time or near full-time regimens.

A randomized clinical trial of prescribed patching regimens of 2 versus 6 hours a day in children between the ages of 3 and 7 with mild to moderate anisometropic or strabismic amblyopia.

Penalization.

Penalization refers to a series technique used to temporarily diminish the vision of the sound eye, thereby encouraging use of the amblyopic eye.

Penalization can be used as a first-line treatment or as a back-up treatment in the event that other therapy fails or compliance is an issue.

Penalization.

Pharmologic PenalizationOptical Penalization

(The instillation of cycloplegic ophthalmic preparations into the sound eye).

(Optical penalization involves altering the spectacle or contact lens correction of the sound eye to produce image blur, providing incentive to fixate with the amblyopic eye).

Refractive SurgeryRefractive surgery has been shown to have a potential role in the treatment of selected children with anisometropic and ametropic

amblyopia.

Photorefractive keratectomy,

LASIK (laser-assisted in situ keratomileusis), and

Clear lens extraction.

Long-term Follow-up.

In general, younger children should be seen more frequently than older children during the treatment

phase of amblyopia.

Thank You.