D - Cataracts 1 - Week -3 Flashcards
State the 3 components of the lens
Capsule
Cortex with endothelium
Nucleus
What two cell types exist within the lens?
Cuboidal cells
Bow cells
Describe the composition of the lens
40-70% water
2-3% salt
30-70% protein
Which lens crystalin is formed foetally?
Gamma
What is the proposed role of alpha and beta crystalin?
Protective
Which crystalline clumps in association with nucleus hardening?
Gamma
Describe the metabolism of the lens
Anaerobic glycolysis in epithelium.
What is produced from lens metabolism and why?
Energy: for Ion pumps, protein synthesis
Glutathione: an antioxidant
How does fluid flux occur through the lens?
Water enters lens via thin posterior capsule
Pumped out of anterior epithelium with NA/K/ATPase
Where do lens fibres meet?
At suture lines
What are lens fibres made up of?
Bow cells which have elongated and lost their nucleus
What does the lens suture look like anteriorly? And posteriorly?
Anteriorly: a Y
Posteiorly: an upside down Y
What causes the yellowing of the lens with age?
Accumulation of chromophores
How does ageing affect the lens? (Other than yellowing) What does this result in?
Posterior capsule thinning. Leads to increased fluid uptake and cataract formation
What are the 4 general types of cataracts?
Artefacts
Congenital
Acquired
Senile
What types of congenital cataracts are there? (2) Which is most common?
Sight debilitating
Non-sight debilitating = most common