To do good research in the field of strabismus, one must think fourth dimensionally—the fourth dimension being time. One needs to know not only the short-term outcome of a given study, but also how those results hold up over time. Frequently manuscripts dealing with strabismus report data on patients who have been followed up for a short while after surgery; the reader never learns how those same patients fare as more time passes. Consequently, McNeer et al are to be heartily congratulated for their article in this issue of the ARCHIVES. They report additional follow-up on a group of patients who were treated with bilateral botulinum toxin type A injections for infantile esotropia. (The initial report has been published.) At first glance, the results they report seem good, so good in fact that the reader must answer the question:“Should botulinum toxin type A be the treatment of choice for infantile esotropia?” As such, the article deserves to be read very critically. After such a reading, I believe the question remains unanswered because of some important unresolved issues.

McNeer et al report that 89% of patients had good alignment with a follow-up of at least 1 year since the last injection. They note that these results are in sharp contrast with those of other reports of the use of botulinum toxin type A in similar patient populations. They do not, however, speculate on why their results are so different from those of other investigators. Conceivably, experience and skill may explain the different results; however, this is unlikely. With this treatment modality, the main challenge for the surgeon is to create a pharmacologic paralysis of the target muscle. As long as the clinician is able to accomplish that, differences in technique probably play a minimal role. One therefore must ask whether the patient populations being treated were different.

All investigators studying the treatment of infantile esotropia are plagued by the problem of inclusion criteria. It is generally agreed that to give a diagnosis of infantile esotropia, strabismus must have been present before 6 months of age. Unfortunately, clinicians rarely have the opportunity to see strabismic children that young, and, consequently, researchers must rely on the history given by the parents or observations made by primary care physicians. I am aware that the naysayers and polemical critics of published studies are quick to point out that these 2 means of diagnosis may be flawed. I also realize this attitude can place an unfair burden on the researchers. Nevertheless, the study by McNeer and coworkers raises serious questions about their patient population. They indicate a mean preinjection deviation of 33.4 prism diopters with a range of 10 to 60 PD in their series of children with infantile esotropia. This is very low. In fact, 15 of 41 patients younger than 12 months of age had pretreatment deviations of 25 PD or less. In my experience, it is rare for a child with infantile esotropia to have a deviation less than 25 PD; I have a hard time accepting their patient mix as representative of infantile esotropia. Von Noorden pointed out that pPD to 62 PD, in my own previously reported series, the mean was 51 PD. Two explanations for this discrepancy seem possible. Perhaps many of the patients of McNeer and coworkers did not have infantile esotropia despite the autors' efforts to keep the population pure. Inadvertent inclusion of patients with acquired esotropia would have skewed the results toward a better outcome. Alternatively, there may have been selection bias. The parents of the patients were given a choice as to whether they wanted incisional surgery or botulinum toxin type A injection. We are not told anything about the number or characteristics of those patients whose parents elected incisional surgery. Were they possibly patients with larger deviations? Such selection bias also could have influenced the results.

Of the patients studied, the deviations in 37 (49%) were well aligned horizontally (by the authors' criteria) with only 1 injection. The remaining patients required multiple injections or their deviations were not acceptably reduced. this is somewhat poorer than most reports on standard incisional surgery. What is more noteworthy is that during a mean follow-up period of about 3 years, 11 patients (14%) required 3 or more procedures, and 6 (8%) had 4 or more. These numbers include only procedures needed to obtain satisfactory horizontal alignment; they do not include procedures to correct dysfunction of the inferior or superior oblique muscles or dissociated vertical divergence. If one includes procedures needed to correct those 2 disorders, the number of patients who need 3 or more procedures would undoubtedly be higher. The number of patients who need a large number of procedures with botulinum toxin type A injection is certainly higher than would be found in a series of patients undergoing incisional surgery. Although McNeer et al point out that botulinum toxin type A injection is simpler and carries less risk than incisional surgery, I believe they have overstated the risks and complications of standard surgery. Also, McNeer et al indicate that late referral compromises the results of incisional surgery in patients with infantile esotropia. It is unclear to me why the factors that lead to delay of incisional surgery until an undesirable older age would not similarly result in delay of treatment with botulinum toxin type A injection. Indeed, almost half of the authors' patients were older than 12 months of age when treated.

Unfortunately, we are not told how many patients did not meet the criterion of 12-month follow-up since the last injection because they needed ongoing repeated injections. Certainly if there were many such patients, one would view these results differently.

In the end, it may be a matter of trade-offs, between which patients and clinicians may have a choice. Standard surgery may provide a higher success rate with a smaller number of procedures; botulinum toxin type A injection may be simpler and quicker, but require more interventions to reach the desired goal.

投稿截止日期为4月1日