Final answer:
Tonometers and dye tests are used to observe the flow of aqueous humor and demonstrate lacrimal system function, respectively. These methods help in the diagnosis of conditions like glaucoma and in the assessment of nasolacrimal duct patency. Eye movement tests assess extraocular muscle function but do not directly observe fluid dynamics within the eye.
Step-by-step explanation:
To observe the flow of aqueous humor or to demonstrate lacrimal system function, a tonometer may be utilized. This device measures intraocular pressure, which can help detect excessive pressures characteristic of glaucoma. When the aqueous humor flows properly, it maintains the eye's moist surface by circulating from the anterior chamber through the lacrimal puncta, and eventually draining into the nasal cavity via the nasolacrimal canal.
In addition to tonometry, dye tests involving the introduction of dyes such as fluorescein can also be used to visualize the flow of fluids through the eye's lacrimal system. For example, the dye can highlight the passage from the lacrimal gland through the lacrimal puncta and sac, and then into the nasolacrimal duct. This is particularly useful in cases where there is suspected blockage or dysfunction within the lacrimal apparatus.
Tests to monitor eye movement, such as having patients follow a stimulant like a pen with their eyes, do not directly relate to the observation of aqueous humor flow, but rather assess the function of extraocular muscles and related neural structures. These tests can identify conditions such as internuclear ophthalmoplegia, which leads to symptoms like double vision.