Nasolacrimal Drainage System Quiz IOA1
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Nasolacrimal Drainage System Quiz IOA1

Created by
@mxrieen

Questions and Answers

What is the thickness of the tear film?

7 to 10 μm

Which layer of the tear film retards evaporation and provides lubrication for smooth eyelid movement?

Lipid layer

What is the primary source of atmospheric oxygen for the cornea?

Tear film

Which substances are contained in the tear film for antibacterial purposes?

<p>Lysozyme, beta-lysyn, lactoferrin, IgA</p> Signup and view all the answers

Which glands contribute to the lipid layer of the tear film?

<p>Meibomian and Zeiss glands</p> Signup and view all the answers

What is the function of the lipid layer in the tear film?

<p>Retards evaporation and provides stability</p> Signup and view all the answers

Which layer of the tear film helps maintain corneal hydration?

<p>Aqueous layer</p> Signup and view all the answers

What percentage of tear fluid passes through the nasolacrimal drainage system?

<p>75%</p> Signup and view all the answers

Where is the lacrimal punctum located?

<p>At the junction of the lacrimal and ciliary portions of the eyelid margin</p> Signup and view all the answers

What prevents retrograde movement of fluid up from the nasal cavity?

<p>Valve of Hasner</p> Signup and view all the answers

What causes tears to be driven into the nasolacrimal duct?

<p>Lacrima sac collapse</p> Signup and view all the answers

What is the length of the interosseous part of the nasolacrimal duct?

<p>12 mm</p> Signup and view all the answers

What is the function of the canaliculi in tear drainage?

<p>Act as siphons to pull tears in through the punctum</p> Signup and view all the answers

Where does the lacrimal sac empty into?

<p>Nasolacrimal duct</p> Signup and view all the answers

Which of the following is a symptom of canaliculitis?

<p>Pain, swelling, erythema, and discharge</p> Signup and view all the answers

What is the normal range for Tear Break Up Time (TBUT)?

<p>Between 15 and 45 seconds</p> Signup and view all the answers

What is the most common congenital lacrimal abnormality?

<p>Congenital Nasolacrimal Duct Obstruction</p> Signup and view all the answers

What is the primary cause of Dacryocystitis?

<p>Obstruction of the nasolacrimal duct</p> Signup and view all the answers

What is the characteristic feature of Congenital Dacryostenosis?

<p>Lacrimation and discharge</p> Signup and view all the answers

What is the recommended action if Congenital Nasolacrimal Duct Obstruction is not relieved 4-8 weeks after birth?

<p>Probing</p> Signup and view all the answers

What is the surgical procedure for acute canaliculitis with a pouting puncta?

<p>A posterior cut down of the canaliculus and curettage of the granules</p> Signup and view all the answers

What is the characteristic feature of Dacryoadenitis?

<p>Pain, edema, and erythema</p> Signup and view all the answers

What is the measure of the stability of the tear film?

<p>Tear Break Up Time</p> Signup and view all the answers

Which component of the tear film is responsible for facilitating adhesion of the aqueous layer to the ocular surface?

<p>Mucous layer</p> Signup and view all the answers

What is the normal total volume of tears on the ocular surface?

<p>7 to 10 μl</p> Signup and view all the answers

What is the average pH of tears?

<p>7.45</p> Signup and view all the answers

Which gland is responsible for reflex secretion of tears in response to a stimulus?

<p>Main lacrimal gland</p> Signup and view all the answers

What is the blood supply for the lacrimal gland?

<p>Lacrimal artery</p> Signup and view all the answers

Which nerve provides sensory innervation to the lacrimal gland?

<p>Trigeminal nerve</p> Signup and view all the answers

How is lacrimal gland fluid distributed over the ocular surface?

<p>Through contraction of the orbicularis muscle</p> Signup and view all the answers

What is the average osmolarity of the tear film?

<p>315 mOsm/kg</p> Signup and view all the answers

Where is the main lacrimal gland located?

<p>Temporal fossa of the orbital plate of the frontal bone</p> Signup and view all the answers

What is the average pH of tears?

<p>7.45</p> Signup and view all the answers

What is the normal tear production rate?

<p>1 μl/min</p> Signup and view all the answers

What is the composition of the main lacrimal gland fluid?

<p>Water, electrolytes, and antibacterial agents</p> Signup and view all the answers

What is the total volume of tears on the ocular surface?

<p>7 to 10 μl</p> Signup and view all the answers

What is the function of the mucous layer in the tear film?

<p>Facilitates adhesion of the aqueous layer to the ocular surface</p> Signup and view all the answers

Study Notes

Anatomy and Physiology of the Tear Film

  • The aqueous layer makes up 60-70% of the total tear film and contains water, electrolytes, inorganic salts, glucose, urea, enzymes, immunoglobulins, cytokines, proteins, peptide growth factors, glycoproteins, and antibacterial substances.
  • The mucous layer, derived from conjunctival goblet cells, comprises 30-40% of the tear film and facilitates adhesion of the aqueous layer to the ocular surface, as well as binding and entrapping bacteria and viruses.
  • Tear film stability is achieved through the even spread of the mucous layer over the corneal epithelium by the eyelids and the absorption of mucous by the glycocalyx to create a hydrophilic surface.
  • The total volume of tears on the ocular surface is 7 to 10 μl, with normal tear production at about 1 μl/min and the eye's capacity to hold 20-30 μl at once.
  • The tear film is normally isotonic and has an average osmolarity of 315 mOsm/kg, which can vary based on factors such as blink rate, humidity, ocular pathology, and contact lens use.
  • The average pH of tears is 7.45, with good buffering ability, allowing the eye to tolerate ophthalmic solutions with different pH levels.
  • The lacrimal secretory system consists of the main lacrimal gland, accessory lacrimal glands (Krause and Wolfring), Meibomian glands, and conjunctival goblet cells, serving the dual function of tear formation and drainage.
  • The main lacrimal gland, located in the temporal fossa of the orbital plate of the frontal bone, has orbital and palpebral lobes and secretes fluid composed of water, electrolytes, and antibacterial agents.
  • The blood supply to the lacrimal gland is through the lacrimal artery, while sensory innervation is provided by the lacrimal nerve, and reflex tearing occurs in response to external stimuli.
  • The tear film is distributed across the ocular surface through the secretion of lacrimal gland fluid into the upper fornix, which descends across the anterior surface of the globe and is spread and reformed with each blink.
  • Both upper and lower eyelid margins have a tear meniscus, with the upper tear meniscus continuous with the lower meniscus and leading directly to punctum in the medial canthus for drainage.

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Description

Test your knowledge of the nasolacrimal drainage system with this quiz. Learn about the components and functions of the system, including the lacrimal punctum, canaliculi, lacrimal sac, and nasolacrimal duct. Understand how tear fluid passes through this system and its importance in maintaining eye health.

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