Aging Changes In The AC/vitreous/lacrimal System Flashcards
An acute rise in EVP results in a _____ ratio of increase IOP
1:1
Conventional pathway
- Cornrealscleral outflow
- TM and SC (main structures)
- IOP dependent
Unconventional pathway
- uveoscleral outflow
- ciliary muscle bundle
- IOP independent
Factors affecting IOP
Peak int he morning
Corneal thickness
Steroid
Outflow obstruction
Occlusive angle
-diabetes, uveitis, hyphema, pseudoexfoliation glaucoma, pigment dispersion glaucoma
Injury to the TM
-Fuchs heterochromic iritis, glaucomatocyclitic crisis
Classic Goldman equation
An acute ride in EVP results in a 1:1 ratio of increase in IOP
Aging changes in anterior chamber
- reduced anterior chamber depth, cortical cataract has more effect on this change
- reduced uveoscleral outflow. Increase in amount of connective tissue in ciliary muscle
- accumulation of extracellualr matrix plaque in TM
- increased outflow resistance in the TM and SC
Vitreous function
Support
Diffuse barrier
Metabolic barrier
Transparency
Vitreous function: support
PVD; macular edema
Vitreous function: metabolic buffer
Reduce neovascularixation in retina
- neovascular glaucoma
- NSC
Vitreous function: transparency
- synchisis scintillations
- asteroid hyalosis
Aging change of the vitreous
The gel structure becomes more liquefied with aging
Breakdown of the vitreous gel and aggregation of collagen fibrils due to increase of liquid potion
Vitreous syneresis
What is the most common cause of pVD
Vitreous syneresis
Floaters
Aggregation of collagen fibrils
Where is the change of the gel of the vitreous most likely to happen with age
In the center
Mucus layer composition
Mucin
Mucus layer functions
- provides medium for aqueous
- cover epithelium
- trap debris and bacteria
Mucus layer sources
- goblet cells (primary)
- squamous cells of cornea and conj
Lipid layer composition
Meibomian oil
Functionsof lipid layer
Slow the evaporation of the awe opus layer
Vitreous compositions
Water Collagen HA Vitreal cells Vitamin C
Functions of lipid layer
Slow the evaporation of the aqueous layer
Sources of the lipid layer
- meibomian gland (primary)
- Zeiss and Moll
Composition of aqueous layer
- water
- electrolytes
- Na and CL (osmolarity)
- K and Ca (cornea epeothelium health)
- proteins
Functions of the aqueous layer
- provide protection
- buffering
- regulation cornea epithelium proliferation’s
Sources of the aqueous layer
Main lacrimal gland
Accessory lacrimal gland
Clinical evaluation for tear secretion
Schirmer 1
Schirmer II
Phenol red thread test
Meinscometry
Clinical evaluation of tear film stability
TBUT
Ocular protection index
Videokeratography
Tear turnover
Clinical evaluation of the tear film osmolarity
Tear film osmolarity
Tear ferining
Tear evaporation
Clinical evaluation of the lipid layer
Inferometry
Meibomtery
Ocular surface clinical evaluation
Fluorescein
Rosa bengal
Lissamine green
Aginging changes of the lacrimal systems
- goblet cell population may decrease
- reduced in tear reflex secretion
- change in composition of the meibomian secretion
- increase of plugged meibomian gland pores
- reduced lacrimal drainage capacity
Major components of the aqueous layer
Water
What are the main contributor fir the osmolarity of the aqueous layer
Na And CL
What are the K and Ca responsible for in the aqueous layer
Corneal epithelium health
Which outflow system is reduced with age
Unconventional
What helps the mucus layer stay stable on the corneal epithelium
Glycocalyx
