Sir,
We thank Dr Franceschetti for his interest in our article. As our title, ‘Efficacy of amblyopia therapy initiated after 9 years of age’ implies, none of the children in our study had undergone a prior ocular examination. Therefore, none had ever worn spectacles, received amblyopia therapy, or had strabismus surgery. It is quite rare that an amblyopia associated with esotropia had never undergone a previous ocular examination until the age of 9 years. Therefore, it is difficult to understand why our title gave the impression that the article was about the usual amblyopia observed in children with convergent strabismus.
As a result of the inclusion criteria according to the age when the amblyopia was detected, most of our patients were related with anisometropia. Therefore, we did not discuss the different types of amblyopia in the discussion.
The term, ‘critical period’ became widely used after Wiesel and Hubel1 presented their experiments on monocular deprivation and discussed the critical period for changes in the ocular dominance of the cells in the primary visual cortex of a cat, as a result of a monocular deprivation of eye opening for several months. Nowadays, different critical periods for different visual functions are used during the development of the visual system.2 As he mentioned, ‘critical period’ is sometimes used for amblyopia with a convergent strabismus, but it is also used for anisometropic deprivation3, 4 as well as a congenital cataract,5 etc.
I cannot completely agree with his opinion in that ‘this article could induce nonspecialists to continue an occlusion on children with convergent strabismus longer than the period for which positive results might be obtained, with the risk of creating irreversible psychological damage.’ Of course, amblyopes related with esotropia showed a worse prognosis to occlusion therapy than the amblyopes related to anisometropia. However, some compliant amblyopes of 11–15 years of age due to a strabismus showed an improvement with a full-time occlusion.6 Occlusion treatment is not simple to implement and is often associated with some degree of distress. Despite this, the negative psychosocial effect might be less than expected.7, 8 Besides, amblyopia by itself has a significant effect on the patients' psychosocial functioning.9 We cannot ignore the psychosocial difficulties related to an amblyopia affecting the individuals' self-image, work, school, and relationships.9
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Hwang, JM., Ahn, J. Reply to A Franceschetti. Eye 20, 122–123 (2006). https://doi.org/10.1038/sj.eye.6701807
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DOI: https://doi.org/10.1038/sj.eye.6701807
