Product Design How much can we do

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Product Design How much can we do?

• Ralph P. Stone, Ph.D.
• R.P. Stone Consulting, Inc.
• Fort Worth, Texas

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Financial Disclosure

• Retired Employee of Alcon Laboratories
• Consultant to Alcon Laboratories

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Serenity Prayer

• Give me the serenity to accept what I cannot
  change
• Courage to change things I can
• And wisdom to know the difference.
• Paraphrased from Reinhold Niebuhr (1892-1971)

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Has the overall rate of infection changed?
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Microbial Keratitis 2008
F Stapleton et al., Ophthalmology 2008
1151655-1662.
6

• The relative risk of daily disposable wear is 1.5
  times the rate of conventional frequent
  replacement daily wear lenses.
• JKG Dart et al., Ophthalmology 2008 115
  1647-1654

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The Lens Care Process
Lens in the eye
Disinfection
Manual Removal
Lens Storage in the Case
Cleaning and rinsing
Rinsing of lenses (optional)
Lens Reinsertion
Lens Case Cleaning
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The Lens Care ProcessPoints of
Contamination/Organism Removal
Disinfection
Manual Removal
Lens Storage in the Case
Lens in the eye
Cleaning and rinsing
Rinsing of lenses (optional)
Lens Reinsertion
Low Levels of Contamination Reducing
contamination Increasing contamination
Lens Case Cleaning
9
The Lens Care ProcessPoints of
Contamination/Organism Removal
Lens in the eye
Disinfection
Manual Removal
Lens Storage in the Case
Cleaning and rinsing
Rinsing of lenses (optional)
Lens Reinsertion
Low Levels of Contamination Reducing
contamination Increasing contamination
Lens Case Cleaning
10
Lenses Aseptically Removed
11
The Lens Care ProcessPoints of
Contamination/Organism Removal
Lens in the eye
Disinfection
Manual Removal
Lens Storage in the Case
Cleaning and rinsing
Rinsing of lenses (optional)
Lens Reinsertion
Low Levels of Contamination Reducing
contamination Increasing contamination
Lens Case Cleaning
12
Patient Compliance with Hand Washing Before Lens
Handling
RP Stone, Poster BCLA 2007 and references therein
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Organisms Recovered After Lens Handling
RP Stone, Poster BCLA 2007 and references therein
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Acanthamoeba in Water

• Evaluation of lakes and tap water in Dallas and
  Tarrant Counties Texas (Stone, preliminary
  unpublished data) lt1 FLA /100ml water, 1
  FLA/ 1,000 ml
• James River, VA samples at 30 sites over Spring
  and Summer along the course of the river to the
  tidal areas (Ettinger et al 2003)
• lt 5 /50 ml
  Acanthamoeba/month
• Rarely isolated
• Acanthamoeba in Belgian thermal polluted
  industrial sites (de Jonckheere1981)
• 0-18
  Acanthamoeba/200 ml
• 11 References in worldwide literature
  quantitating FLA in environmental samples (DT
  John 1995)
• 1 FLA / 2.6-6.0 Liters (average 1
  FLA/ 4.2 liters)
• Levels in the water column were measured in two
  SC ponds/lakes (Kyle 1986, 1987)
• 0.2-1.2 Acanthamoeba/ml

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The Lens Care ProcessPoints of
Contamination/Organism Removal
Lens in the eye
Disinfection
Manual Removal
Lens Storage in the Case
Cleaning and rinsing
Rinsing of lenses (optional)
Lens Reinsertion
Low Levels of Contamination Reducing
contamination Increasing contamination
Lens Case Cleaning
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Contribution of Cleaning and Rinsing
Log Reduction
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What we didnt learn from the historical data

• The real capacity to remove organisms
• The lenses were rubbed and rinsed with hands in
  sterile gloves
• The difference is recontamination from
  organisms on the hands versus just removal by
  the process
• All the old studies were using separate cleaners
  and products that required significant rinsing
  often to reduce irritation.

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Calculated Organisms Remaining After Soak Only
Regimen(based on load of 10,000 bacteria)
Using worst case results for 4 commercial
products from R. Rosenthal et al., CLAE 26
17-25, 2003
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Storage of lenses and Challenge with Fusarium
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Risk of Infiltrate or Infection
f (Number of Organisms)
f(Corneal Damage)
f (Time)

X
X
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Risk of Infiltrate or Infection
f (Number of Organisms)
f(Corneal Damage)
f (Time)

X
X
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The Lens Care ProcessPoints of
Contamination/Organism Removal
Lens in the eye
Disinfection
Manual Removal
Lens Storage in the Case
Cleaning and rinsing
Rinsing of lenses (optional)
Lens Reinsertion
Low Levels of Contamination Reducing
contamination Increasing contamination
Lens Case Cleaning
23
Organisms Recovered After Lens Handling
RP Stone, Poster BCLA 2007
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The Lens Care ProcessPoints of
Contamination/Organism Removal
Lens in the eye
Disinfection
Manual Removal
Lens Storage in the Case
Cleaning and rinsing
Rinsing of lenses (optional)
Lens Reinsertion
Low Levels of Contamination Reducing
contamination Increasing contamination
Lens Case Cleaning
25
Compliance with Case Cleaning
R. R. Stone Poster BCLA Poster 2007
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Contamination of Lens Cases
T. R. Gray et al., BJO 1995 79601-605
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T. R. Gray et al., BJO 1995 79601-605
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Formation of Biofilms

• The formation of biofilms is simple and involves
  initial approach of organisms by electrostatic
  and physical forces.
• Cells stick by secretion of an extracellular
  polymer matrix
• This facilitates reproduction and formation of a
  glycocalyx
• Unlike planktonic organisms Organisms in a
  biofilm have organization even though they do
  not show any genetic differences

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Eliminating Biofilms

• Stewart and Costerton report that biofilms can
  raise antibiotic resistance as much as 1000 fold.
  
• In other fields high levels of chlorine, ozone
  and 10 hydrogen peroxide are used to disinfect
• For Contact Lens cases only heat e.g., boiling
  water for 10 minutes will control biofilms.

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Conclusion

• Even without rubbing and rinsing the primary
  source of patient exposure to microorganism comes
  from
• Lens Handling
• Contamination of lens cases

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Suzanne FleiszigGlenn Fry Award Lecture

• Based on derived assumption (of infections), the
  contact lens industry has spent millions of
  dollars developing a plethora of new products,
  none of which have significantly impacted the
  incidence of infection during the 30 years since
  soft contact lenses have been on the market.

S.M.J. Fleiszig Optometry and Vis. Sci. 2006
83(12) E866-E873
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Thank you
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References

• E Poggio etal., N ew Eng. J. Med. 1989
  321(12) 779- 783.
• KH Cheng et al. ,The Lancet 1999 354181-184.
• SE Nilsson et al. , CLAO J. 1994 20(4) 225-230.
• F Stapleton et al., Ophthalm. 2008
  1151655-1662.
• JKG Dart et al., Ophthalm.. 2008 115 1647-1654
• M Mowrey Mckee et al., CLAO J. 1992 18 87-91
• M Mowrey Mckee et al., CLAO J. 1992 18 240-4
• DHart and K. Shih, Am J Optom. Physiol Optics
  1987 64(10) 739-748
• D Hart, W Reindel et al. Opt and Vis. Sci. 1993
  70(3) 185-191
• R Stone, Poster Presented 2007 BCLA Annual
  Clinical Meeting, Manchester, England
• RD Houlsby et al., J Am .Opt. Assoc. 1984
  55205-211
• K Shih, J Hu and M Sibley, 1985 12(4)235-242
• MR Ettinger et al. Parasitology Research 2003
  89(1) 6-15
• JF de Jonckheere. J Protozoology 1981
  28(1)56-59
• DT John, MJ Howard. Parasitology Research
  199581(3)193-201
• DE Kyle, GP Noblet, J. Protozoology 1986 33(3)
  422-434
• DE Kyle, GP Noblet, J. Protozoology 1987
  34(1)10-15
• RA Rosenthal et al., CLAE 2003 26 17-25,
• HK Dannelly and RV Waworuntu, Eye and Contact
  Lens 2004 30(3) 163-165