BT outcomes under open versus closed sky technique
Reviewed by Fiona Rowe

This retrospective study compared open versus closed sky BT injection techniques without electromyography (EMG) control in 135 patients (31 open sky and 104 closed). Patients were aged 1-50 years for open sky and 2-34 years for closed. There was a significantly greater angle correction with closed sky than open. Mean eso correction was 6.86PD for open sky and 22.41PD for closed at three-months follow-up and 12.11PD vs 21.59PD at six-months follow-up. Mean exo correction was 9.27PD for open sky and 21.13PD for closed at three-months follow-up, and 8.06PD and 24.31PD at six-months. A higher dose of BT injection per muscle was recorded for closed sky. Success rates at six months were 59.3% for open sky and 43.6% for closed, despite larger angle correction with closed sky. Complications were typical with ptosis and vertical deviations, and similar to published reports. The authors recommend closed sky technique without EMG guidance as success rates were not significantly better with open sky versus closed. Success rates were comparable to studies using EMG guidance and they were able to avoid additional anaesthesia and with shortened procedure time without EMG.

Botulinum toxin injection in horizontal rectus muscles without electromyography using an open sky vs a closed sky technique.
Kassem RR, Badr RAA, Al Zarea BKA, et al.
JOURNAL OF PEDIATRIC OPHTHALMOLOGY AND STRABISMUS
2022;59(6):388-95.