What is the best practice to prevent systemic absorption of eye drops?

Applying gentle pressure to the inner canthus, which is the corner of the eye closest to the nose, is an effective strategy to prevent systemic absorption of eye drops. This technique minimizes the amount of medication that drains into the tear duct, thereby reducing the risk of the drops entering the systemic circulation.

When pressure is applied to the inner canthus, it occludes the nasolacrimal duct, which is responsible for draining tears (and any instilled medication) into the nasal cavity. By blocking this duct for a short period after administering the drops, you can significantly limit the amount that might otherwise be absorbed through the mucosal surfaces of the nose and further into the bloodstream.

Other practices, like instilling drops with the head tilted back or immediately closing the eyes after instillation, do not address the key pathway of systemic absorption through the tear drainage system. Using a larger drop size is generally not recommended, as larger drops do not necessarily improve efficacy and can lead to more medication being lost due to overflow, which can also increase side effects and waste. Hence, applying gentle pressure to the inner canthus is recognized as the best practice in this context.