What is amblyopia and how does it develop?
Amblyopia occurs when defective vision (short-sightedness, long-sightedness, astigmatism), unilateral strabismus or, for example, unilateral clouding of the eye lens or drooping of the upper eyelid occur in early childhood and prevent a sharp image. To prevent blurred vision or double vision, the visual impression of the worse eye is suppressed by the brain. The result is an underdevelopment of the visual center in the brain – the eye becomes “weak-sighted”.
Vision and eye cooperation develop particularly in the first few months of life and are still susceptible to disorders up to the age of around eight to ten years. Amblyopia, or the causes that lead to it, must be recognized and treated early. Poor eyesight that has not been adequately treated can no longer be successfully treated in adulthood. Patients with amblyopia have no spare eye in the event of an accident or illness of their ‘good’ eye and are particularly at risk of losing their better eye. In addition, lateral visual acuity can be important for your child’s career choice.
Amblyopia: causes and risk factors
Strabismus and defective vision often run in families. Risk factors include prematurity, hereditary diseases, cerebral palsy and syndromes (e.g. trisomy 21).
Amblyopia: early detection
It is assumed that the visual system is mature at the age of eight to ten – after that, treatment of amblyopia promises less success. It is therefore important to recognize and treat amblyopia and its causes at an early stage. This is why pediatricians examine a child’s eyes and vision at an early age as part of statutory early detection. Attend the preliminary examinations with your child. Amblyopia is often accompanied by strabismus. No child is too young for an orthoptic assessment. Consult an ophthalmologist and an orthoptist for a diagnosis, as strabismus does not progress with age. Even a slight squint can cause severe amblyopia.
Amblyopia: Diagnosis with us
Orthoptists, orthopaedic surgeons and ophthalmologists work hand in hand in the orthoptic department of the USZ Eye Clinic. The orthoptist determines a so-called orthoptic status. The main focus is on determining visual acuity, diagnosing strabismus, testing eye cooperation, eye mobility and pupil function. The examination methods are adapted to the child’s age and stage of development. Orthoptists at the USZ can already determine the visual acuity of infants. The ophthalmologist performs a lens test with eye drops to rule out defective vision and checks whether the eye is healthy. Our experienced orthopaedists, orthoptists and doctors are used to dealing with (small) children and the examinations do not require any active cooperation from the child.
Amblyopia: Prognosis
Low vision’ is usually completely treatable with early diagnosis and treatment. As parents, you can contribute a great deal to the success of the therapy:
- Let your child choose the motifs for the eye patches themselves.
- Carry out the therapy consistently and integrate it into your daily routine
- Inform caregivers at the daycare center or teachers and involve them in the therapy.
- During cover therapy, you could look at books with your child, draw, play, do homework or, exceptionally, give them the tablet to play with (the eye should actively ”work” for proximity).
- Possibly work with a reward system and build in fixed times for therapy.
The success of the masking therapy essentially depends on whether you and your child follow the masking therapy prescribed by the orthoptist or orthopaedist.
Amblyopia: Treatment
If your child has a high and/or uneven visual defect, your child will be prescribed glasses. If the visual acuity of the affected eye remains reduced despite wearing glasses, a masking treatment with a masking plaster with a colorful motif is started. This therapy is the best method. Alternatively, masking films can be stuck to the lens, but this requires that the glasses are worn well. More rarely, a fabric eye patch or pupil-dilating eye drops are used to nebulize the better eye.
The good eye is covered to activate visual development in the eye with poorer vision. The duration of the covering is adjusted individually, depending on the age of the child and the severity of the visual impairment. Regular checks are carried out to see whether the visual acuity of the worse eye improves. The aim is to achieve equal visual acuity for near and far. This is usually only achieved after months to years. Subsequently, a reduced period of coverage may be necessary to maintain visual acuity until around the age of 10. After that, the risk of the eye becoming weak-sighted again decreases.
An existing strabismus or defective vision is not corrected by the masking treatment. Conspicuous strabismus can be improved after masking treatment with eye muscle surgery, but a high degree of defective vision usually remains.