Sub-Tenon block: a learning curve of 100 cases

Area of Science:

• Ophthalmology
• Anesthesiology
• Surgical Education

Background:

• Sub-Tenon blocks are an alternative to peribulbar blocks for ophthalmic surgery.
• Understanding the learning curve is crucial for safe and effective block administration.

Purpose of the Study:

• To evaluate the learning curve for performing sub-Tenon blocks among anaesthetists experienced in peribulbar techniques.
• To establish criteria for a successful sub-Tenon block and assess factors influencing its efficacy.

Main Methods:

• Two anaesthetists performed sub-Tenon blocks for cataract and vitreo-retinal surgeries.
• Criteria for a good block included chemosis, subconjunctival hemorrhage, globe movement, and need for additional block.
• Success rates and complication rates were tracked over procedures.

Main Results:

• Overall success rates were 72% and 56% for the two operators.
• 10% of cases required an additional peribulbar block.
• The need for additional blocks and improved globe movement plateaued around 60 procedures.
• Chemosis and subconjunctival hemorrhage rates did not correlate with increased experience.

Conclusions:

• Anaesthetists skilled in peribulbar blocks can achieve proficiency in sub-Tenon blocks after approximately 60 procedures.
• While globe movement and need for supplementary blocks improve with experience, chemosis and hemorrhage rates remain consistent.
• Sub-Tenon blocks are a viable option for both cataract and vitreo-retinal surgeries.