Affiliations : Saint-Georges Hospital, Beirut, Lebanon
Journal reference: doi: 10.1016/j.jfo.2015.03.010
Summary: Inward crossed-eyes or esotropia is the deviation of one or both eyes towards the nose – which could lead to permanent lazy eye (or amblyopia). In this article Dr. Fakhoury describes the Faden operation, a new surgical intervention to treat inward crossed-eyes.
What is esotropia?
While strabismus means abnormal deviation of the eye (in any possible direction), esotropia, one of the two most common types of strabismus with exotropia, is the inward deviation of the eye, which means deviation of one or both eyes towards the nose. It is usually apparent in childhood and noticed by parents at an early stage but can also be observed in adults. Like any eye deviation, it should be examined and treated in children as soon as possible to avoid leading to a permanent decrease in vision known as lazy eye or amblyopia.
What is amblyopia?
Amblyopia is the inability of one or both eyes to reach 20/20 vision despite the absence of organic causes. Each child is born with a low vision that increases with age and for this vision to reach 20/20, it should be constantly stimulated. Anything that impedes vision, whether it is very high degrees in one eye, eye deviation, or cataract, can lead to suboptimal vision development.
Since we need two identical images to superimpose by the brain to form a unified image, if one eye produces a blurred image for any of the above mentioned reasons, the brain will automatically stop using that eye and rely on the image of the other, causing alterations of neurological development of the other eye, stopping it from reaching a 20/20 vision later in life.
Treatment of amblyopia
There are several treatments for amblyopia all of which are only effective before the age of 8 or 9, when the brain is plastic enough to reverse the process. This is why it is the current recommendation that all children be examined at the age of three for a general checkup where the ophthalmologist will look for eye deviations and will place special drops to examine the anatomy and structure of the eyes, and look for any degrees such as myopia, astigmatism and hypermetropia.
Treatment of esotropia to avoid irreversible strabismus and amblyopia
In this study we examined the effect of performing strabismus surgery in 55 children who have esotropia. Esotropia comes under 3 types: The first accommodative type can simply be corrected with eyeglasses. The second partially accommodative type can be corrected to some extent with eyeglasses although the eyes continue to deviate slightly and often end up requiring surgical intervention. The third non-accommodative type can only be corrected with strabismus surgery. The study grouped children with the second (partially accommodative = 29 subjects) and third (non-accommodative = 26 subjects) types of esotropia.
The esotropia surgery we conducted is called a Faden operation and is usually done in the operating room under general anesthesia. In order to straighten the eyes, the ophthalmologist works on the eye muscles attached to the globe of the eyes using a non-absorbable suture thread, a step called myopexia that is performed alone or combined with conventional surgery, depending on different components of the deviations. The primary goal is to obtain the smallest possible stable residual angle while retaining long-term stability with the least possible number of surgeries. It is important to note that some children will need more than one surgery throughout their life to correct any residual or relapse of the deviation.
Take home message
Our study confirms the efficiency of Faden operation as a surgical intervention to treat partially and non-accommodative esotropia. However, the study also highlights a progressive loss of efficacy of this surgery in the long run. It is thus mostly interesting for non-accomodative esotropia where surgical intervention remains the only treatment option.