Amblyopia, also known as lazy eye disease, afflicts 2-4% of the Brazilian population, including adults and children. It is the main cause for unilateral low sight in children and adults below 60 years old. It is more common in children with family backgrounds, premature or delayed development births, but can nonetheless occur in any child.
Amblyopia reduces sight in one or both eyes, even with the use of optical corrections (glasses or contacts).
The afflicted eye shows no anatomical changes, as it is a fault in the visual system development during infancy.
Loss of sight due to amblyopia can be avoided and reverted with early detection and intervention. Thus, it is important for children with or without risk of amblyopia to be identified in the early infancy, when there is a better prognosis for successful treatment.
Causes
- Strabismus: one of the most common forms of amblyopia, which develops in the deviated eye. To avoid diplopia (double vision), the brain suppresses the sight of the deviated eye, and the child develops sight only in the eye that fixates on images.
- Non-corrected Refraction (power): the most common form. There are two types
- Anisometropic amblyopia is when only one of the eyes has reduced refractive power and the other eye has good sight. Thus, the brain is unable to understand blurred images from the bad eye and suppresses that sight. The eyes of a child with anisometropic amblyopia usually appear normal to the family and pediatrician, which may delay detection and treatment.
- Isoametropic amblyopia is when both eyes have a strong non-corrected refractive error, causing bilateral low sight. This happens due to the harmful effect of unfocused retinal images on the immature visual system.
- Visual Deprivation: the least common and most severe cause. It occurs due to ocular abnormalities that obstruct the visual axis or interferes with central sight and stops the development of the visual system. Examples include: congenital cataract, eyelid ptosis (drooping), or periocular injuries that cover the visual axis, cornea opacities, vitreous hemorrhage.
Treatment
Treating amblyopia involves the following steps:
- Eliminating (if needed) any obstructions to the visual axis, such as cataract, as soon as possible.
- Correcting any significant refraction errors with glasses or contacts.
- Forcing the use of the amblyopic eye by limiting the use of the better eye with the regular use of eye-patches (occlusion).
Lack of adherence to the treatment is a common problem that can extend the treatment period or cause it to simply fail. Due to that, we must stress how important it is for the disease to be understood and the child, and parents and family members, to persevere.
Sight develops until around the age of seven, so amblyopia must be treated as soon as possible to obtain a better prognosis.