PII: S0161-6420(03)01041-8

Abstract

The recent article by Uddin and Davies described treatment of upper eyelid retraction associated with thyroid eye disease with subconjunctival botulinum toxin injection.1Uddin J.M. Davies P.D. Treatment of upper eyelid retraction associated with thyroid eye disease with subconjunctival botulinum toxin injection.Ophthalomology. 2002; 109: 1183-1187Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar They described a new way of injecting botulinum toxin into the subconjunctival space of the tarsal plate. Such an injection is easy to perform, and localization of the injection site is also easy. Their results were encouraging, and they claimed that the upper lid–lowering effect lasted between 1 and 40 months.However, in another study by Ozkan et al,2Ozkan S.B. Can D. Soylev M.F. et al.Chemodenervation in treatment of upper eyelid retraction.Ophthalmologica. 1997; 211: 387-390Crossref PubMed Scopus (36) Google Scholar the duration of action of botulinum toxin in treating a similar condition lasted only as long as 4 months. It has been reported that functional recovery of the neuromuscular junction by nerve sprouting and muscle reinnervation occurs within 2 to 4 months after botulinum toxin injection.3Davis E.C. Barnes M.P. Botulinum toxin and spasticity.J Neurol Neurosurg Psychiatry. 2000; 69: 143-147Crossref PubMed Scopus (42) Google Scholar It would therefore be surprising to find a botulinum toxin effect persisting up to 40 months. If we analyze Uddin and Davies' Table 2, those patients with a follow-up period longer than 35 weeks (except patient 3) had more than one injection given. However, data on the time intervals between the last botulinum toxin injection and the last follow-up in these patients were not reported. A follow-up period of 40 months in a patient who has received more than one injection does not mean that the botulinum toxin effect has lasted for 40 months. The duration of effect should be counted from the date of the last injection. If patient 3 was excluded, all the patients who had been given one injection were only followed up for 12 months. Without the missing data, it would be difficult to assess the effectiveness of botulinum toxin in Uddin and Davies' study. The recent article by Uddin and Davies described treatment of upper eyelid retraction associated with thyroid eye disease with subconjunctival botulinum toxin injection.1Uddin J.M. Davies P.D. Treatment of upper eyelid retraction associated with thyroid eye disease with subconjunctival botulinum toxin injection.Ophthalomology. 2002; 109: 1183-1187Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar They described a new way of injecting botulinum toxin into the subconjunctival space of the tarsal plate. Such an injection is easy to perform, and localization of the injection site is also easy. Their results were encouraging, and they claimed that the upper lid–lowering effect lasted between 1 and 40 months. However, in another study by Ozkan et al,2Ozkan S.B. Can D. Soylev M.F. et al.Chemodenervation in treatment of upper eyelid retraction.Ophthalmologica. 1997; 211: 387-390Crossref PubMed Scopus (36) Google Scholar the duration of action of botulinum toxin in treating a similar condition lasted only as long as 4 months. It has been reported that functional recovery of the neuromuscular junction by nerve sprouting and muscle reinnervation occurs within 2 to 4 months after botulinum toxin injection.3Davis E.C. Barnes M.P. Botulinum toxin and spasticity.J Neurol Neurosurg Psychiatry. 2000; 69: 143-147Crossref PubMed Scopus (42) Google Scholar It would therefore be surprising to find a botulinum toxin effect persisting up to 40 months. If we analyze Uddin and Davies' Table 2, those patients with a follow-up period longer than 35 weeks (except patient 3) had more than one injection given. However, data on the time intervals between the last botulinum toxin injection and the last follow-up in these patients were not reported. A follow-up period of 40 months in a patient who has received more than one injection does not mean that the botulinum toxin effect has lasted for 40 months. The duration of effect should be counted from the date of the last injection. If patient 3 was excluded, all the patients who had been given one injection were only followed up for 12 months. Without the missing data, it would be difficult to assess the effectiveness of botulinum toxin in Uddin and Davies' study.