CL Care & Compliance

Question 1

State 6 infectious microorganisms which can manifest due to poor care of lenses

Answer 1

Fusarium solani
Candida albicans
Acanthamoeba
Staph- aureus
Pseudo- aeruginosa
Serratia marcescens

Question 2

Describe 4 ocular defence mechanisms

Answer 2

Blinking/tearing
TF Proteins (lysozyme, lactoferrin, immunoglobulins)
Tight junctions (corneal epithelium)
Cell sloughing

Question 3

How can CL challenge ocular defences?

Answer 3

greatly alters blinking/tearing effect (microorganisms hide behind lens)
can alter defence mechanisms (sloughing) and introduce a lot of microorganisms into ocular surface

Question 4

Describe the 4 main ingredients/components of CL solutions

Answer 4

Surfactants (hydrophilic/phobic ends, micelle forms around lipid droplets ~ soluble/removal) such as poloxamer, poloxamine

chelating agent (EDTA) binds to Ca in competition with proteins (anti-microbial effect as Ca metabolises cell wall)

Buffers (pH stability - borate, phosphate, citrate)

Active ingredient

Question 5

Describe the composition/use of hydrogen peroxide as a solution

Answer 5

3% conc. very effectve against trophozoites/acanthamoeba cysts but complicated/possible toxic reaction

2-step (pyruvate/catalase catalyst) or 1-step with inherent neutralisation

Question 6

Explain peroxides MoA and its trade offs

Answer 6

broad spectrum action: makes hydroxyl free radicals to attact lipids/proteins of cells

auto-neutralisation, 1 step poorer disinfection than 2 step, kills Acanthamoeba bacteria