5 Questions
What is the approximate percentage of water in the normal human lens?
66%
Which part of the lens is more hydrated than the other?
Lens cortex
What is the significance of maintaining water and electrolyte balance in the lens?
It is crucial for lens transparency
What is the characteristic of cortical cataracts in terms of water content?
Water content rises significantly
What is the concentration of potassium in the lens?
120 millimolar (mM)
Study Notes
Lens Composition
- The normal human lens is composed of approximately 66% water and 33% protein, with little change in this proportion with aging.
Lens Hydration
- The lens cortex is more hydrated than the lens nucleus.
- About 5% of the lens volume is comprised of water found between the lens fibers in the extracellular spaces.
Ion Balance
- Sodium and potassium concentrations within the lens are maintained at 20 millimolar (mM) and 120 mM, respectively.
Lens Physiology
- The mechanism that controls water and electrolyte balance is critical to lens transparency.
- Perturbation of cellular hydration can readily lead to opacification.
Cataracts
- Disruption of water and electrolyte balance is not a feature of nuclear cataracts.
- In cortical cataracts, the water content rises significantly.
Learn about the composition of the human lens, including water and protein proportions, and how cation balance is maintained in the lens.
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