How can systemic absorption of Minims Lidocaine & Fluorescein be reduced during and after instillation?

Systemic absorption of Minims Lidocaine & Fluorescein may be reduced by compressing the lacrimal sac at the medial canthus for one minute during and following instillation, blocking passage through the naso-lacrimal duct to the nasal and pharyngeal mucosa; this is especially advisable in children.