Anatomy and physiology of the eye: lacrimal pump failure: practice question

A Ophthalmology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Ophthalmology · Anatomy and physiology of the eye: lacrimal pump failure

Sample item

A 40-year-old man with a complete left lower motor neuron facial palsy complains of persistent watering of the left eye, though Schirmer testing is normal and syringing is patent. What is the main mechanism?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Loss of orbicularis oculi pumping of tears into the sac

Blinking contracts the orbicularis, including its lacrimal part, creating a pump that draws tears into the canaliculi and sac. In facial palsy this pump fails and the lower lid sags, so tears overflow despite a patent system.

Option by option

  • A. Obstruction at the valve of Hasner

    Patent syringing excludes obstruction at the lower end of the duct.

  • B. Stenosis of the common canaliculus

    Patent syringing also excludes canalicular stenosis.

  • C. Hypersecretion by the main lacrimal gland

    Normal Schirmer values exclude hypersecretion as the cause.

  • D. Loss of orbicularis oculi pumping of tears into the sac (correct)

    Correct. Paralysis of orbicularis oculi stops the lacrimal pump and lid apposition.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is D, Loss of orbicularis oculi pumping of tears into the sac. Blinking contracts the orbicularis, including its lacrimal part, creating a pump that draws tears into the canaliculi and sac.

Why is "Obstruction at the valve of Hasner" not the answer?

Patent syringing excludes obstruction at the lower end of the duct.

Why is "Stenosis of the common canaliculus" not the answer?

Patent syringing also excludes canalicular stenosis.

Why is "Hypersecretion by the main lacrimal gland" not the answer?

Normal Schirmer values exclude hypersecretion as the cause.

What concept does this question test?

It tests Anatomy and physiology of the eye: lacrimal pump failure in Ophthalmology. In facial palsy this pump fails and the lower lid sags, so tears overflow despite a patent system.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Anatomy and physiology of the eye: lacrimal pump failure?

Group the red eye by what to examine and what the pupil does. Then use the flashcards and the other Ophthalmology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.