Which structure should be inspected for patency during fluorescein examination?

Which structure should be inspected for patency during fluorescein examination?

• A. Inferior oblique muscle
• B. Nasolacrimal puncta
• C. Optic nerve
• D. Lens capsule

Answer: (B)

Fluorescein examination can reveal how well tears drain, not just where you see staining. The structure checked for patency is the nasolacrimal puncta, the small openings at the medial canthus that admit tears into the canaliculi. After applying fluorescein, observe whether dye passes through these puncta and drains toward the nose, indicating an open drainage pathway. If dye fails to exit or remains stagnant, there may be obstruction downstream in the lacrimal system. The other structures—the inferior oblique muscle, the optic nerve, and the lens capsule—do not participate in testing tear drainage patency with fluorescein.

Fluorescein examination can reveal how well tears drain, not just where you see staining. The structure checked for patency is the nasolacrimal puncta, the small openings at the medial canthus that admit tears into the canaliculi. After applying fluorescein, observe whether dye passes through these puncta and drains toward the nose, indicating an open drainage pathway. If dye fails to exit or remains stagnant, there may be obstruction downstream in the lacrimal system. The other structures—the inferior oblique muscle, the optic nerve, and the lens capsule—do not participate in testing tear drainage patency with fluorescein.