Strabismus and amblyopia
What is strabismus?
Strabismus (squint) is a very common condition of childhood with incidence of 4%. It is a condition where the optical axes of the 2 eyes are not aligned. In strabismus, when one eye looks straight, the fellow eye deviates inwards or outwards.
Strabismus may manifest itself the first few months of life, mainly in the form of inward deviation (esotropia) or after 18-24 months when the toddler starts focusing on close objects.
When a child presents with a squint, there needs to be proper examination to diagnose whether this is a true or a pseudo squint mainly in ages younger than 3-4 months, as extraocular muscles and vision has not developed fully yet. Common causes of pseudo squint are epicanthus and wide shaped nose. A pseudo squint does not need any treatment and will normally resolve with time. A true squint must be corrected promptly to avoid, apart from a cosmetic problem, development of amblyopia as well. The deviating eye in a child gradually becomes ‘lazy’ and is unable to see clearly, even with the use of spectacles. This condition cannot be treated after the first decade of life and a lazy eye will always remain lazy.
Early diagnosis and proper management will help avoid this.
Management of squints
A child presenting with a squint must be examined by an ophthalmologist in order to establish the type and cause of it. Visual acuity check and refraction with dilating drops must be performed for accurate measurement of glasses while fundoscopy must be performed as well to rule out any abnormalities.
There are cases of squints that improvement can be achieved just with the use of spectacles that need to be constantly worn and checked every 6-12 months.
Esotropia is usually associated with hypermetropia that increase till the age of 6 years, stabilises by the age of 8 and gradually decrease till the age of 14. Gradual reduction in the power of the spectacles is accompanied by reduction of the level of the squint.
Squints that do not correct with glasses need to be managed with surgery. During the surgical intervention we weaken or strengthen the muscles to align the eyes. In cases where there is a complex or major squint, one surgical intervention may not be enough.
It is very important to stress the importance of preschool check even if the parents have not observed any problem with their child.
What is amblyopia?
Amblyopia or ‘lazy’ eye is not only caused by strabismus. Great differences in the refractive status of the 2 eyes, e.g. unilateral high congenital myopia (anisometric amblyopia), conditions that block the light from reaching the back of the eye, e.g. eyelid ptosis, congenital cataract, significant refractive errors, usually hypermetropia (ametropic amblyopia), non corrected astigmatism (meridian amblyopia) and other conditions like congenital nystagmus can cause amblyopia.
It is a relatively common condition as about 7% of the general population has some degree of amblyopia that developed in childhood.
Treatment of amblyopia
A complete and thorough ophthalmological examination will ensure the correct diagnosis and prevention of amblyopia. The first step is to cover the good eye so that the child will only use the amblyopic eye, which will gradually develop the correct level of vision.
The younger a child is at the time of diagnosis, the higher is the potential of vision. It should be emphasised that if the diagnosis is later than the age of 7-8, in most cases amblyopia is not treatable.
For the success of the specific treatment technique, it is very important for the parents to be positive and persistent as young children will find it very difficult to accept covering of their good eye.
Covering of the eye needs to be done a few hours a day for as long as necessary and this depends on the level of the amblyopia and treatment compliance.
In young children improvement is very quick but the child still needs to be followed up regularly until the age of 8 to avoid recurrence.
Finally, please remember: An ophthalmologist is the best source for providing responsible answers in matters that affect the health of your eyes. In no way is the information received from our website a substitute to that. Always refer to your eye specialist for advice.