To prevent eye medications from entering systemic circulation, pressure should be applied to which area?

Applying pressure to the nasolacrimal sac is crucial for preventing eye medications from entering systemic circulation. When eye drops are administered, they can easily drain into the nasolacrimal duct, which leads to the nasal cavity and subsequently can be absorbed systematically, potentially leading to unwanted side effects.

By applying pressure to the nasolacrimal sac, you physically block this duct, minimizing the flow of the medication away from the eye and helping to ensure that more of the drug remains in the ocular area for localized treatment. This technique enhances the efficacy of the medication and reduces the likelihood of systemic absorption and adverse reactions.

The other areas mentioned do not serve the same function in this context. The nasal cavity is farther downstream in the drainage pathway, the outer canthus has no significant role in this process, and while the inner canthus is near the eye, it does not specifically block the drainage of the medication as effectively as the nasolacrimal sac does.