Abstract
Purpose: :
Infantile Esotropia (IE) has a prevalence of 0.27-2% depending on the definition, the population studied and whether or not children with nervous system impairment are included. The purpose of this study was to explore the possibility of a sub-classification of IE, based on a new working definition. It could be helpful on deciding on early or late surgery.
Methods: :
IE was defined, adapted from the working definition for cerebral palsy by the Surveillance of Cerebral Palsy in Europe Study Group, as a group of permanent, but not unchanging, disorders with strabismus and disability of fusional vergence and binocular vision, due to a nonprogressive interference, lesion, or maldevelopment of the immature brain, the orbit, the eyes, or its muscles, that can be differentiated according to location, extent, and timing of the period of development. An exploratory differentiation into IE with and without nervous system disorder and early-onset accommodative esotropia was applied to two populations: 303 children with amblyopia in The Hague, recruited in 2002-05 and children visiting the outpatient clinic in the Sophia Children’s Hospital. In the second group we documented background clinical characteristics like nervous system disorders and perinatal problems.
Results: :
During the 2.5 year period the study in The Hague was conducted, the diagnosis of IE was made in 23 children; 9.2 children/year. The birth rate in The Hague averaged 4,262, indicating a prevalence of 0.22% (= 9.2/4,262). 85% had been diagnosed before the age of 5 years. In five children, the presence of latent nystagmus and/or dissociated vertical deviation had been diagnosed after the age of six months. In our outpatient population with IE, 37% had a gross nervous system disorder (e.g. hydrocephalus, perinatal asphyxia).
Conclusions: :
The new working definition leaves room for both IE with and without any nervous system disorders and early-onset accommodative esotropia. The prevalence found in the study in The Hague is an underestimation, as only IE with amblyopia had been included and children with any gross nervous system disorder had been excluded. In the outpatient population we found that more than a third had a gross nervous system disorder related to the university-hospital setting. The subdivision of IE helps to differentiate children who have a chance to retain binocular vision with early strabismus surgery from those who have not.
Keywords: strabismus • strabismus: treatment