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7 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What are the 5 layers of the tear structure |
1. Lipid Layer 2. Aqueous Layer 3. Mucus Layer 4. Microvilli 5. Corneal Epithelium |
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Origin of lipid, aqueous and mucous layer |
LIPID: Meibomian glands Glands of zeis Glands of moll
AQUEOUS: Lacrimal gland Gland of krause Gland of wolfring
MUCOUS: Globlet cells Gland of manz Lacrimal Gland Non-goblet cells Crypt of henle
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What is the drainage system composed of? |
Puncta Canaliculi Lacrimal sac Nasolacrimal duct Valve of hanser |
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Some of the functions of tear film: |
Optical: Provides a smooth optical surface
Mechanical: Lubrication Flushes away debris Removes water from cornea
Nutrient: Oxygen and nutients
Defence: Antibacterial agents
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What can we assess to see if tear film is normal? |
- Tear volume (schirmer test) and production (cotton-thread test)
-tear evaporation rate (evaporimeter) 10-40% of tears are lost by evaporation.
-tear film stability (break-up time)
-lipid layer thickness (tearscope-plus)
-ocular surgace quality (fluoresein or rose bengal staining) |
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What happens of tear film does not function properly? |
Ocular irritation, tear film instability and ocular surface disease-------> Dry eye: caused by deficient tear production and/or excessive tear evaporation. -most common in old people |
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Describe a clinical and research test to measure tear vol/prod |
CT Schrimer test- 5x30mm fold 5mm, Insert for 5 mins, norm avg 22mm, dry avg 7.6mm. RT Flurophotometry Best way to determine tear vol, |
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