Orthoptics for children

Strabismus visible and latent

Strabismus is an eye disorder in which there is a misalignment between the visual axes: it may be present at birth or appear later. The earlier the appearance of strabismus, the more serious the disorder is.

Parents of the patient may notice that the child “squints” continuously (manifest strabismus) or only in certain moments (latent strabismus). It is vital that any child manifesting such symptoms be examined immediately.

When a child shows signs of strabismus it is important to exclude the presence of any kind of ocular anomaly which may impair the vision in one eye (congenital cataract, vitreous opacity, retinal disorders, congenital glaucoma, …) and exclude any endocranial problems.

Strabismus is very often associated with refractive errors (hypermetropia, astigmatism, myopia), and is usually characterised by anisometropia (different refractive error in the two eyes).

The ophthalmic-orthoptics itinerary of the young patient

  1. The child squints
  2. When this child comes to our practice, ocular motility is examined to see if this is in fact a case of strabismus. In some cases, children seem to have a squint because the facial bones have not yet developed (pseudostrabismus) yet the visual axes are perfectly parallel.
  3. Cycloplegic drops are prescribed to USE AT HOME (we prefer children not to have any unpleasant experiences in our practice, where we want them to feel at ease at all times) which temporarily paralyse accommodation which can be very healthy in children and therefore tend to partly hide the refractive error.
  4. The child returns for the cycloplegic eye examination, after having put in the eye drops at home.
    The eye examination itself occurs in a state of cycloplegia (dilated pupils and paralysed accommodation) in order to:
    • Examine carefully all ocular segments to exclude the presence of congenital cataracts, vitreous opacity, retinopathy, opticopathy, congenital glaucoma, endocranial disorders.
    • Precisely quantify the refractive error.
  5. If a refractive error is found, a suitable correction is prescribed (glasses) for the young patient, to balance the two eyes. GLASSES MUST BE WORN PERMANENTLY.
  6. The child returns for a check-up after 15/30 days

It has been observed that:

With glasses, the child keeps his EYES STRAIGHT!

A child has ACCOMMODATIVE STRABISMUS, that is ocular misalignment due to the effort made by the eye to compensate for a refractive error.
Cancelling out this effort with glasses, the eye is at rest and the child is able to keep his/her eyes straight.
The child must wear the glasses all the time to consolidate the balance achieved (orthophoria).

IMPORTANT

  1. The glasses must NEVER be removed
  2. The glasses may be removed only for face-washing and for sleeping. On these occasions, the parents must not worry if the child squints more than before: this occurs because the glasses interrupt a vicious circle of accommodation-convergence and at first the child “LOSES CONTROL” without the glasses.
  3. The child is kept under strict observation to ensure ideal correction (since this changes over time as the eyes grow) so that the child’s eyes remain straight and develop a perfect binocular function (collaboration between the two eyes).
  4. At a later stage the child must do orthoptic exercises to learn how to disassociate accommodation and convergence and thereby keep the visual axes straight even without glasses.
  5. At the same time, as the child grows, the hypermetropic refractive error (which always underlies accommodative strabismus) tends to diminish spontaneously. This means that the child needs progressively “weaker prescription” (LESS STRONG) glasses over the years.
  6. Accommodative strabismus has an excellent prognosis over time.

With glasses, the child squints LESS than before!

A child has PARTIALLY ACCOMMODATIVE STRABISMUS, that is there is only a partial ocular misalignment caused by the effort the eye makes to compensate for the refractive error.
Using glasses to cancel out this effort the eye is at rest BUT A RESIDUAL STRABISMUS REMAINS.

The child must wear glasses all the time.
In the case of a residual angle the two eyes are physiologically unable to work together at the same time.
It is essential to use a patch over one eye, alternating between the eyes depending which eye is dominant.
Patching aims to prevent AMBLYOPIA (reduced visual capacity in an otherwise morphologically normal eye) in the “lazy” eye or in the one with a greater refractive error.

IMPORTANT

  1. The glasses must NEVER be removed.
  2. The glasses may be removed only for face-washing and for sleeping. On these occasions, the parents must not worry if the child squints more than before: this occurs because the glasses interrupt a vicious circle of accommodation-convergence and at first the child “LOSES CONTROL” without the glasses.
  3. The child is kept under strict observation to ensure ideal correction (since this changes over time as the eyes grow) and to adjust the patching depending on the clinical results.
  4. If the strabismus angle is different for long and short-distance vision, specific bifocal glasses may be successfully used.
  5. In some cases the child must do orthoptic exercises to learn how to disassociate accommodation and convergence.
  6. If the child achieves a balanced visual acuity in both eyes and a perfect motor alternation (ability to see perfectly well with either eye) yet a strabismus angle remains, a surgical operation is advisable.

With glasses, the child squints THE SAME as before!

A child has NON ACCOMMODATIVE STRABISMUS, that is the ocular misalignment is purely motor in origin.
This type of strabismus may affect children with no refractive error.
In the case of a refractive error, the child must anyway wear glasses all the time.
In the case of a STRABISMUS ANGLE the child is physiologically unable to use both eyes at the same time. It is essential to use a patch over one eye, alternating between the eyes depending which eye is dominant.
Patching aims to prevent AMBLYOPIA (reduced visual function in an otherwise morphologically normal eye) in the “lazy” eye or the one with the greater refractive error.

IMPORTANT

  1. In the case of a refractive error the glasses must NEVER be removed.
  2. The child is kept under strict observation to ensure ideal correction (since this changes over time as the eyes grow) and to adjust the use of the patch depending on the clinical results.
  3. When the child reaches a balanced visual acuity in both eyes and a perfect motor alternation (ability to see perfectly well with either eye) yet a strabismus angle remains, a surgical operation is advisable.
  4. This type of strabismus is much less common than other types.
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