DIS - Ocular Ageing and Histopathology - Week 1 Flashcards
List four major eye diseases are common with age and an approximate percentage of incidence at age 75.
Cataract 50%
Glaucoma 4-8%
AMD - 4-10%
Diabetes - 8-12%
At what age does ageing become a major risk factor for eye disease?
> 60
Can biological functions be kept going indefinitely if maintained optimally?
No, all biological functions have a finite and natural lifespan, even if optimally maintained
What leads to the onset of age-related disease?
Genetic and environmental factors through lifestyle and exposure result in tissue becoming taxed beyond their regenerative capacity
Can epigenetic factors slow down or stop diseases?
Slow down yes, but cannot stop them
How do cells lose their capacity to replicate? What is the exception?
Telomeres shorten with increasing number of mitoses
Except in stem cells
What two external reactions contribute to protein dysfunction?
Increasing amounts of advanced glycation end-products (AGEs)
Increasing UV exposure promotes protein crosslinking (forming aggregates)
In what way can tissue dysfunction occur due to exaggerated normal interactions?
Progressive lipid deposition of cholesterol/lipid on elastin, reducing BV elasticity
What is a consequence of increased elastase expression and does it increase or decrease with age?
Increased elastase expression with age limits build up of inflexible elastin
What is the mechanism behind mitochondrial ageing and what is a consequence of this (2)?
Due to changes in mDNA, resulting in reduced ATP production and increased free radical production
What happens to cellular autophagy with age and what is a consequence of this?
Decreases, resulting in a reduced ability to eliminate abnormal byproducts
List 7 major ageing changes of the eye (including diseases).
Presbyopia
Age related lens pathology (cataract)
AMD
Primary glaucoma
Ateriosclerotic retinopathy
Vitreous liquefaction
Retinal and corneal dystrophies
What is the most common form of ocular pathology encountered by eyecare practitioners?
Age related cataract
How many forms does age-related cataract have and when do they occur? List them and briefly describe their appearance.
Nuclear - milky-yellow
Anterior cortical - spokes/wedges
Posterior subcapsular
They often occur together
List the mechanism of age-related cataract (for each form).
Nuclear - fibre cell compaction in the nucleus (gamma protein aggregation)
Anterior cortical - fibre cell degeneration, liquefaction, and fragmentation
Posterior subcapsular - cytokine-induced abnormal epithelial proliferation
Describe the specific lens changes that occur in age related nuclear cataract including why it appears yellow, changes to the refractive index, and a consequence of this on visiond.
Fibres become more compact, increasing its density, causing the selective absorption of blue light, resulting in a yellowed lens - called bruescence
Denser tissue causes an increase to refractive index, causing a myopic shift
What happens to the crystalline deposits with cataracts and what does this cause?
They are reflective, causing glare
Describe how the lens cortex contributes to age-related nuclear compaction.
Compartment formation by the cortex results in higher tissue density in the nucleus