Page 1 of 1: changes with contact lens

hardcoremallu · Credits: 14733 My Scrapbook My Reading List 6 Books

Contact lens wear is proven to have deleterious effects on the corneal Physiology which of the following statements is incorrect in connection with contact lens wear?
1 The level of glucose availability in the corneal epithelium is reduced.
2 There is a reduction in hemidesmosome density.
3 There is increased production of CO2 in the epithelium.
4 There is a reduction in glucose utilization by corneal epithelium

bhavu · Credits: 9481 My Scrapbook

answer should be 4.
due to contact lens level of glucose availability may be reduced but how can glucose utilisation capacity of cornea reduced???
so i think answer should be 4.

captainprasun · Credits: 1651 My Scrapbook

answer is 3..

glucose supply comes more from aqueous
oxygen comes form air....so in lens...increase co2 accumulation

bhavu · Credits: 9481 My Scrapbook

thanks captain

hardcoremallu · Credits: 14733 My Scrapbook My Reading List 6 Books

if there is increased co2 accumulation...then the answer shud be 4, isntit?

captainprasun · Credits: 1651 My Scrapbook

may be u are right....
but cant rule out 3 also...any one with firm answer?

captainprasun · Credits: 1651 My Scrapbook

may be u are right....
but cant rule out 3 also...any one with firm answer?

hardcoremallu · Credits: 14733 My Scrapbook My Reading List 6 Books

Effect of contact lens wear on epithelial metabolism.
A. Normal state. Most of the oxygen diffuses through the tears from the atmosphere; glucose is supplied by the aqueous humor; carbon dioxide is released into the atmosphere; lactate diffuses into the aqueous humor.
B, During polymethylmethacrylate lens wear, oxygen supply and carbon dioxide release are impaired and must occur through passage of tears beneath the lens. As a result of hypoxia, glucose demand and lactate production are increased.
C, During hydrophilic contact lens wear, oxygen supply is improved because some oxygen can pass through the lens, but glucose demand and lactate production are increased moderately.
D, With highly oxygen-permeable rigid contact lenses, oxygen supply, glucose demand, and lactate production are near normal.
1) During hypoxia.
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Glucose utilization by anaerobiosis(so increased utilization because of block in kreb,s cycle.)
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lactate accumulate and it increasesosmotic solute load
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It leads to stromal edema and reduction in hemidesmosome activity.

sajjanshenoy · Credits: 4274 My Scrapbook

How can ans 1 be true ? "The level of glucose availability in the corneal epithelium is reduced." Glucose comes mainly from the anterior chamber by diffusion from aqueous humor. If contact lens is used, how can glucose availability at the level of the epithelium be decreased ?

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