Abstract:

Objective To assess botulinum toxin treatment in consecutive esotropia due to overcorrection of intermittent extropia. Design Retrospective case series. Participants 15 consecutive esotropia patients who completed more than 6 months follow up after botulinum toxin injection. Methods Botulinum toxin was injected into medial retus bilaterally in each patient based on the angle of esotropia. Main Outcome Measures At each visit, before and after injection, diplopia and eye motility were assessed. Deviation was measured with prism alternative cover test. Binocular vision was checked with synoptophore and Yan Shao Ming random dots stereoscopic chart. Complications of ptosis and vertical deviation were also recorded. Results The average esotropia was 18.71±6.02 PD. These eyes were injected with 2.83±1.02 U botulinum toxin. Consecutive esotroia was significantly reduced in the latest follow-up. Diplopia diminished in 13 cases. Only one case had residual constant exotropia. The other eyes resided with diplopic esotropia.  Convergence fusion range was enlarged, accomparied with a tremendous improvement when assessed with both synoptophore and stereoscopic chart.  One case of ptosis and 3 cases of vertical deviation occurred right after the injection, all recovered in 6 weeks. Conclusion Small angel consecutive esotropia, due to overcorrection of intermittent extropia can be treated using botulinum toxin with up to 85% success rate. The improved convergence and stereopsis may help to stabilize the orthoptic eye alignment. Given high success rate, reversible complications and less invasion, botulinum toxin is suggested to be the first line treatment in consecutive esotropia secondary to overcorrection of intermittent extropia. （Ophthalmol CHN， 2019, 28： 145-149）

Key words: consecutive esotropia, botulinum toxin, intermittent exotropia