modified block 12 Flashcards
the coventional AH pathways is also called
corneoscleral
main structures in the conventional AH pathway
TM and SC
which AH pathway is IOP dependent
conventional path
the unconventional AH pathway is also called
uveoscleral
main structure in the unconventional path
ciliary muscle bundle
which AH pathway is IOP independent
unconventional path
what are 3 big factors that affect IOP
- peak in morning
- corneal thickness
- steroids
if a cornea is thicker than normal, how will the IOP be affected
abnormally high reading
2 ways to obstruct outflow
- occlusive angle
- injury to TM
what are possible causes of an occlusive angle (5)
- severe diabetes
- uveitis
- hyphema
- pseudoexfoliative glaucoma
- pigment dispersion glaucoma
what are possible causes of injury to TM (2)
- fuch’s heterochromic iritis
- glaucomatocyclitic crisis
an acute rise in EVP result in what
1:1 ratio of increase IOP
4 main aging changes to the anterior chamber
- reduced depth
- reduced uveoscleral outflow
- extracellular matrix plaque in TM
- increased outflow resistance in the TM and SC
what has a big effect on the anterior chamber depth
cortical cataract
whey is there a reduction in uveoscleral outflow with age
increase in the amount of connective tissue in ciliary muscle
5 components of vitreous
- water
- collagen
- hyaluronic acid
- vitreal cells
- vitamin C
what makes up 99% of the vitreous
water
what 2 components give vitreous the gel like texture
collagen interacting with hyaluronic acid
4 major functions of the vitreous
- support
- diffuse barrier
- metabolic buffer
- transparency
what can affect the “support” function of the vitreous
PVD
also macular edema
what can affect the “ metabolic buffere” function of the vitreous
- reduce neovascularization in retina
- neovascular galucoma
- NSC
what can affect the “ transparency” function of the vitreous
- synchisis scintillation
- asteroid hyalosis
accumulation of choesterol within vitreous
synchisis scintillations
accumulation of calcium within vitreous
asteroid hyalosis
the “metabolic buffer” function of the vitreous: it is a reservoir for what
- vitamin C
- potassium
- glucose/glycogen
what happens to the vitreous with age
it becomes more liquified
the breakdown of the vitreous gel and aggregation of collagen due to increase of liquid portion
vitreous syneresis
what is the msot common cause of PVD
vitreous syneresis
what is a floater
aggregation of collagen
change of gel structure most likely occur in what part of the vitreous
center
what are the 3 layers of TF (from cornea to air)
mucus layer
aqueous layer
lipid layer
Composition of: mucus layer
Mucin
Composition of: lipid layer
Meibomian oil
Composition of: aqueous layer
- water (mainly)
- Na and Cl (osmolarity)
- K and Ca (corneal epithelium health)
- Protein
Function of: mucus layer
- provide medium for aqueous layer
- cover epithelium
- trap debris and bacteria
Function of: aqueous layer
- provide protection
- buffering
- regulate cornea epithelium proliferation
Function of: lipid layer
Slow the evaporation of aqueous layer
Source of: mucus layer
- primary: goblet cells
- squamous cells of cornea and conj
Source of: aqueous layer
- main lacrimal gland
- accessory lacrimal gland
Source of: lipid layer
- primary: meibomian gland
- zeis and moll
Tests for tear secretion (4)
- schirmer 1
- schirmer 2
- phenol red thread test
- meinscometry
Tests for tear film stability (4)
- TBUT
- ocular protection index
- videokeratography
- tear turnover
Tests for tear film osmolarity (3)
- tear film osmolarity
- tear Ferning
- tear evaporation
Tests for lipid layer evaluation (2)
- interferometry
- meibometry
Tests for ocular surface evaluation (3)
- fluorescein
- Rosa bengal
- lissamine green
Secreted by the corneal epithelium
- helps mucus layer stay stable on the corneal epi
Glycocalyx
Aging changes of the lacrimal system (5)
- dec in goblet cells
- reduced tear reflex secretion
- change in composition of meibomian secretion
- increase of plugged meibomian
- reduced lacrimal drainage
