EST: CL effects on ocular physiology (oxygen related)

Question 1

what are the 3 effects that CL can have of ocular physiology? briefly describe each of them

Answer 1

1. hypoxia
   low levels of oxygen
2. hypercapnia
   Accumulation of CO2
3. disrupted tear film
   CL wearers are 5 x more likely to complain of dryness compared to specs wearers

Question 2

explain how corneal hypoxia happens

Answer 2

oxygen supply decreases, anaerobic respiration occurs

generates lactic acid & carbon dioxide in stroma, causes endothelial pump dysfunction

Stromal Acidosis - uptake of water into stroma

to corneal oedema and potential cell damage

Question 3

what oxygen transmissibility? what is the recommended dK/t for short term and extended wear? what is the general advise for dK/t?

Answer 3

ability of the lens to allow O2 to move from anterior to posterior surface

short term: 35
extended wear: 125

Practice Advise: For extended SCL wearers with , to prescribe SCL with Dk/t > 90