Data values Flashcards
Lens: UV absorption and transmit visible light. give wavelengths.
UV absorption 300-400nm, transmit visible light 400-700nm.
Gross lens anatomy: average adult dimension.
equator:
axial thickness:
power:
anterior surface radius of curvature:
posterior surface radius of curvature:
equator: 10mm
axial thickness: 4mm
power: 15D
anterior surface radius of curvature: 10mm
posterior surface radius of curvature: 6mm
Lens. described as onion with around (…) fine layers of varying refractive index.
22 000
lens. *refractive index gradient contributes to (…) of total lens power change (accommodation in monkeys)
65%
Lens capsule: variable thickness. thickest in equator (…) and thinnest posterior pole (…)
equator: 20um
posterior pole: 3um
lens capsule has multiple basement membranes (… units)
40
Lens central zone. cell types. range of cell diameters. average height (…) and width (…). contains organelles typical of epithelial cells.
height: 6um. width 13um.
Lens proper (fibres). extend (…) in length. added throughout life (… fibres/(unit))
10mm in length. 5 fibres/day
lens shell formation. (…) shells/(unit) added after age of (…)
5 shells/year, added after age 5.
lens. an aged lens has around … lens fibres and … shells.
3.6 million lens fibres and 2500 shells.
lens sutures. foetal lens have … point suture, while adults have … point suture.
3-point suture, 9-point suture for adults.
Lens substance has …% protein, …% water. compared to cornea with …% protein.
35% protein, 65% water (cornea 20% protein)
lens substance has …% carbohydrate and ions; critical to normal lens functioning
<1%
Lens. Transparency. Paracrystalline protein structure, usually small soluble ordered proteins (~…kDa MWt)
20-30
Lens. transparency. Proteins >… kDA MWt diffract light, dilute solutions scatter light
50
