Term
| The excretory pathway of lacrimal drainage begins at what structure? |
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Definition
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Term
| The punctum opens into what structure? How long is it? |
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Definition
The cannaliculi
It is 10 mm long total but it is 2mm down and 8mm across |
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Term
| The cannaliculi is lined with what type of cells? What encircles it? |
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Definition
It is lined with stratified squamous epithelium.
It is encircled by the orbicularis muscle |
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Term
| The naso lacrimal sac and duct are lined with what type of cells? |
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Definition
| Nonciliated columnar epithelium |
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Term
| About 10 to 25% of the secreted tear volume is lost by what? What happens to the rest of the tear volume? |
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Definition
Evaporation
The rest gets drained into the nasal passage and some may be absorbed into the nasolacrimal system |
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Term
| What are the two most important mechanisms for lacrimal drainage? |
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Definition
| The dynamic effect of the lids and the medial canthus apparatus |
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Term
| The Lacrimal Pump theory postulated by Jones and Jones and Wobig proposes what? |
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Definition
| That the contraction of the pretarsal orbicularis muscle during eyelid closure compresses and shortens the cannaliculi, pumping the tears towards the lacrimal sac. He further proposed that the tears are sucked from the cannaliculi to the sac by negative pressure during the closure of the eyelids during a blink. |
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Term
| The Doane Theory conradicted Jones' theory and propsed what? |
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Definition
| That the siphoning of the tears by the lacrimal sac occurs during the relaxation of the blink (opening) rather than at the closure. |
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Term
| Temporal paralysis of the medial orbicularis muscle with what toxin caused a decrese in tear outflow and has been suggested as a possible therapy for dry eye? |
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Definition
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Term
| The main routes of tear loss have been identified as nasalacrimal duct drainage and absorption, as well as evaporation. What is the structure that "picks up the slack while sleeping" by carrying away any residual tears left at night? |
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Definition
| Conjunctival pump - Na+K+ATPase pump |
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Term
| What is an overflow of tears called? |
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Definition
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Term
| Describe the movement of the tear film towards lacrimal drainage. |
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Definition
| Lids close in a zipper like fashion pushing the tears along the lacrimal river or tear meniscus/prism toward the puncta. The tears move into the puncta due to capillary attraction |
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Term
| What is the Marangoni effect? |
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Definition
| It says that because of the surface tension and hydrostatic flow gradient, the lipid layer of the tears drags the water layer with it |
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Term
| What drains 60% of the tear layer due to, among other things, gravity |
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Definition
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Term
| The Jones Test 1 tests how open the lacrimal drainage mechanism is. What is the procedure for this test? |
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Definition
NaFl 3x with strip in cul-de-sac
wait 1 min
blink forcefully
blow 1 nostril
If there is nothing present in the tissue after 5 mins, there may be a blockage somewhere in the drainage system |
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Term
| What is the problem with the Jones 1 test? |
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Definition
25% of normals give a negative test
Possible explanation - person (especially younger person) has a very high tear turnover rate |
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Term
| What is the Jones 2 test? |
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Definition
Done after Jones 1 -
irrigate and dilate puncta
insert syringe and inject saline
If nothing still drains, there is a total obstruction
If saline shows, there is a blockage near the puncta |
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Term
| What is the Micro-Reflux test? |
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Definition
Instill 2 drops of NaFL
5 blinks to activate lacrimal pump
counterclockwise massage over nasolacrimal sac
Positive (blockage) if reflux of NaFL stained tears from inferior punctum after first cycle of massage empties canaliculus |
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