11 - contact lens solutions

How quickly does a biofilm or pellicle form on a soft CL?

minutes

What can deposit on a soft CL?

1. protein

2. lipid

3. calculi (jelly bumps)

4. iron, calcium

5. microbes

how do proteins appear as deposits on a SCL? does alcohol remove prtn?

hazy, flat

will not remove with alcohol

how do lipids appear as deposits on a SCL? does alcohol remove lipids?

shiny, not wettable

will remove with alcohol

what is the grading scale in-vivo visible deposition?

clear (G0): 0% surface coverage

light (G1): 25%

medium (G2): 50%

heavy (G3): 75%

very heavy (G4): 100%

what amount of bacteria is in the normal flora of lids and conjunctiva compared to cornea?

lids and conj: 90% staph, 80% proprionibacterium, 20% corynebacterium

cornea is relatively sterile

What type of bacteria is contact lens wear infection associated with compared to non-CL wear infections?

contact lens: gram -

non contact lens: gram + → rare in adulthood

what gram + bacteria is usually seen in non-CL wearers?

S aureus

S pneumoniae

What are the functions of CL solutions?

1. disinfect/clean

2. surface wettability

3. keeps lens hydrated

4. mechanical buffer btwn lens and cornea

what are the cleaning levels of efficacy?

1. sterilization

2. disinfection

3. preservation

Is sterilization bactericidal or bacteriostatic?

bactericidal

is disinfection bactericidal or bacteriostatic?

both

is preservation bactericidal or bacteriostatic?

bacteriostatic

What is a D-value?

exposure time to kill 90% (1 log unit) of an organism

What is a good D-value?

lower values = greater efficacy

What is on the FDA organism panel that a CL solution must kill in order to be approved? What is not on it?

Staph aureus

Serracia marcesans

Pseudomonas aeruginosa

Candida albicnas

Fusarium sofani

NO ACANTHAMOEBA

What are the two categories of FDA approval contact lens solutions (describe them)?

regimen solution: rub, rinse, soak

disinfecting solution: rinse + soak (no rub)

Which of the two categories of contact lens solutions have a higher log reduction of bacteria + fungi with a soak?

disinfecting solution

What are the major components of contact lens solution?

1. disinfectants/preservatives/chelating agents

2. surfactants

3. lubricating agents

4. wetting agents

What are the minor components of a contact lens solution?

1. tonicity

2. pH/buffers

3. stabilizers

what are the 3 most common disinfecting agents?

1. PAPB (polyaminopropyl biguanide)

2. POLYQUAD (polyquaternium-1)

3. Benzyl Alcohol

what is benzyl alcohol used for?

lipid removal

what are the functions of chelating agents?

1. acts synergistically with other agents to improve disinfection or cleaning

2. binds tightly to metal ions needed for cell wall synthesis

What are examples of chelating agents?

1. EDTA → improves disinfection

2. citrate → ptn removal

3. hydroxyalkylphosphonate → ptn removal

What do surfactants in a CL solution do?

cleans → detergents solubilise debris from lens

wet → change charge of surface (makes it less hydrophobic)

what are examples of surfactants?

1. poloxamine

2. CP-ED3A

3. isopropyl alcohol

what do lubricating and wetting agents do to SCL?

demulcents → water soluble polymer used to lubricate mucous membranes and improve comfort

what are the functions of hydrogen peroxide?

kill bacteria and fungi

used as a disinfectant at 3% and preservative

what is required when using hydrogen peroxide at higher levels?

neutralization

What GP cleaners/solutions are non-abrasive?

MPS (multiple purpose solution)

1. Unique pH

2. Clear Care/Clear Care Plus

3. Tangible Clean

Which soft contact lens solutions use Polyquad only as its preservative?

Optifree Express/PureMoist/RepleniSH

Which contact lens solutions use both Polyquad and a Biguanide preservative?

Biotrue

disregard

disregard

Which contact lens solutions have the highest rate against acanthamoeba? What stages do they kill?

1. Opti-free Puremoist: trophozoite only

2. Acuvue Revitalens: both forms

3. Clear Care (hydrogen peroxide): both forms

what must you do if you know a lens came in contact with Acanthamoeba?

DESTROY IT

what is the disinfection procedure for multi-patient use diagnostic gas permeable CL?

1. place 3% hydrogen peroxide with GP in non-neutralizing case

2. disinfect 3+ hrs

3. rinse with MPS, pat dry and store dry

what is the disinfection procedure for multi-patient use soft CL?

1. place 3% hydrogen peroxide with SCL in non-neutralizing case

2. transfer SCL to neutralizing case with fresh H₂O₂ and neutralizing disc or tablet

3. neutralize for 6+ hrs

4. rinse with MPS, store in disinfected case with MPS

what behaviors do we desire for our patients?

1. hand-washing

2. proper case cleaning and regular lens/case replacement

3. proper care of lenses/use of system

4. no contact with water

when do you wash your hands when handling CL?

before insertion and removal

What increases the number of CFU on a CL?

handling the lenses

How often should you replace a CL case?

every 3 months

what is the proper case cleaning/drying technique?

1. dump all solution every morning

2. place clean tissue or paper towel on counter

3. rinse case with CL solution → NOT water

4. place case and lids upside down on tissue to dry during the day

this is a fill in the blank question on the exam

should SCL ever come in contact with water?

NO →

no shower in lenses

no swimming in lenses without goggles

no hot tubs

what should cleaners be rinsed with?

1. saline

2. CL solution