Amblyopia, also known as lazy eye, is a reduced visual acuity in one or both eyes that can occur even without visible eye problems. Amblyopia develops when the brain does not learn to see and interpret images correctly due to insufficient stimulation during the critical early years of life. It is the most common cause of one-sided vision loss in childhood and affects approximately 2–5% of all children.
This developmental defect of the visual pathways can be caused by various factors. In the case of refractive errors, light is not focused on the retina, resulting in blurred vision. If this is not corrected with glasses, it can lead to amblyopia. Similarly, this developmental defect can be caused by strabismus (crossed eyes) or, less commonly, by structural anomalies such as a drooping eyelid or corneal scars.
Amblyopia is the leading cause of vision loss in children and can lead to permanent visual impairment if left untreated. Early diagnosis and treatment are crucial, as the condition is typically not correctable after the visual development phase is complete.
Visual ability develops during the first years of life: the brain learns to process images from both eyes into a single three-dimensional picture. If one eye consistently receives unclear or conflicting signals during this sensitive phase, the brain increasingly "switches off" that eye. The longer this condition remains untreated, the more difficult it becomes to restore full visual acuity.
Children typically do not notice one-sided visual impairment on their own – they don't know any different. This is why regular eye examinations are particularly important. Possible signs include:
Even in newborns, the pediatrician checks the red reflex and eye alignment. From preschool age, targeted visual acuity tests are possible. Modern photoscreening devices can detect risk factors even in infants.
The goal of therapy is to force the weaker eye to work so that the brain learns to use its signals. Treatment is more effective the earlier it begins, ideally at preschool age, but progress is still possible in school-age children up to about 14 years.
Many children with refractive amblyopia first need appropriate glasses. Simply wearing glasses consistently can significantly improve the visual acuity of the weaker eye.
The better-seeing eye is covered with an eye patch for several hours a day, forcing the weaker eye to be actively used. The daily wearing time depends on the severity of the amblyopia and is individually determined by the ophthalmologist.
Tips for patching:
As an alternative to patching, the stronger eye can be temporarily blurred with atropine drops. This method is particularly suitable for children who do not tolerate the patch.
Newer treatment methods use digital technologies. For example, virtual reality headsets or special games that specifically stimulate the weaker eye. These approaches are still in clinical trials but show promising results.
Initial progress is often visible after just a few weeks, but the entire treatment frequently extends over months to years. Even after visual acuity improves, therapy is gradually reduced to prevent relapse. Regular ophthalmological check-ups accompany the entire course of treatment.
Untreated amblyopia leads to permanent visual impairment that can no longer be corrected even with the best glasses or surgery in adulthood. This makes it all the more important that children receive early eye examinations – especially when risk factors such as strabismus, premature birth, or eye diseases in the family are present.