Final answer:
The mass under the medial canthus likely represents lacrimal fluid accumulation due to nasolacrimal duct blockage, which may cause swelling and potentially affect intraocular pressure if left untreated.
Step-by-step explanation:
The mass under the medial canthus could refer to a range of conditions but commonly represents material such as lacrimal fluid accumulated due to blockage or swelling in the nasolacrimal duct system. The medial canthus is the corner of the eye nearest to the nose, where the upper and lower eyelids come together, and it is closely related to the lacrimal bone, which houses the nasolacrimal canal. This canal allows the drainage of lacrimal fluid (tears) into the nasal cavity.
Lacrimal fluid is essential for keeping the eye moist and is usually drained through the nasolacrimal duct, extending from the lacrimal fossa down into the nasal cavity behind the inferior nasal concha. A blockage in this system can result in a mass or swelling noticeable at the medial canthus. The force exerted by such a mass on the eye can be significant, and if unchecked, might lead to potential damage as with any substantial pressure or force applied on the eye region mentioned in the reference to intraocular pressures and their potential impact on eye health.