Ophthalmic anaesthesia

Question 1

What is the average globe length?

Answer 1

23mm

Question 2

What constitutes a “long eye”?

Answer 2

> 26mm

Question 3

When is a “long eye” suspected?

Answer 3

Myopia (short sightedness)

Question 4

What procedures is the occulocardiac reflex most commonly seen?

Answer 4

Paediatric cases
Squint surgery
Vitreoretinal surgery

Question 5

What is the trigger for the occulocardiac reflex?

Answer 5

traction of the extraoccular muscles, especially the medial rectus, and pressure on the globe.

Question 6

Describe the course of the occulocardiac reflex.

Answer 6

tension on muscles -> long and short cilliary nerves synapse in the gasserion ganglion (short cilliary also traverses the cilliary ganglion) - > trigeminal nerve synapse in the brainstem at the sensory nucleus of the trigeminal nerve -> short intra nuchal fibres synapse in the vagus motor nerve -> vagus nerve projects to the SAN.

Question 7

What is a suitable pre-medicant for a paediatric case for prevention of the occulocardiac reflex.

Answer 7

Glycoperronium 4mcg/kg IM 30-60 mins pre-induction