Risk Factors for Consecutive Exotropia

To the Editors: I read with interest the article, “Analysis of Risk Factors for Consecutive Exotropia and Review of the Literature” by Yurdakul and Ugurlu.1 The authors are to be congratulated in documenting their findings of increased risk factors for the development of consecutive exotropia such as anisometropia, amblyopia, and postoperative adduction defects. The authors reported that “no attempt was made to evaluate the timing of surgical alignment of infantile esotropia.” However, it should be pointed out that statistical analysis has proven that surgical alignment prior to 2 years of age in the treatment of infantile esotropia has resulted in a greater percentage of functional cure with fusion and gross stereoacuity as demonstrated in a monofixation syndrome result.2 In fact, there has also been statistical evidence that alignment prior to the age of 1 year with a duration of misalignment of younger than 1 year results in a greater percentage of patients with a functional cure that includes stereopsis.3 Birch et al.4 also established that stereopsis and long-term stability is inversely proportional to the duration of the misalignment. Yurdakul and Ugurlu state that in their study, “most of the patients (who were infantile esotropes) had surgery after 2 years of age and no significant differences were noted regarding the development of fusion and stereopsis.” This latter finding by the authors was consistent with the fact that only a few patients developed fusion or a monofixation syndrome result. The monofixation syndrome is a relatively stable subnormal binocularity5 and, if this functional result had developed during the course of treatment of the infantile esotropes, it would have probably reduced the chance for consecutive exotropia. von Noorden,6 a long-time skeptic of the value of early surgical alignment in the management of infantile esotropia, declared in his Jackson Memorial Lecture in 1988, “Surgical alignment before the completion of the second year of life improved the chances for an optimal treatment result” (p.1). The authors of the current study said it best, “Because fusion is an important stabilizing factor, in the absence of any useful binocular vision, consecutive exotropia can slowly develop weeks, months, or years after esotropia surgery.” There have been significant studies showing that failure to achieve alignment and a functional cure, such as the monofixation syndrome, in infantile esotropia within the first 2 years of life should be added to the risk factors for developing consecutive exotropia in the treatment of infantile esotropes.