presentation ahearn
TRANSCRIPT
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 1/21
Protective Applications, LLC – D.G. Ahearn1
Microbiological Testing for Contact Lens
CareProducts Workshop – Jan 22, 2009
Acanthamoeba
D.G. Ahearn
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 2/21
Protective Applications, LLC – D.G. Ahearn2
ARVO Poster 2008
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 3/21
Protective Applications, LLC – D.G. Ahearn3
Original 9/12/07Rev. 12/16/07 (REC)D.G. Ahearn
Acanthamoeba keratitis
Acanthamoeba keratitis (AK) is a rare infection of the eye mostly associated with
contact lens wear. The first recognitions of the disease, in the mid-1970’s, followed
traumatic implantation of soil and vegetation, but thereafter to the current date,
about 90% of infections have been reported among soft contact lens users without
histories of overt trauma. The incidence of AK in the USA may be estimated at 1-2
per million per year among contact lens users, at least 10-fold the incidence of
non-users. The CDC, promoted by an apparent upswing of AK in Illinois (Joslin et
al., Am J. Ophthalmol, 142:212, 2006; Am J Ophthalmol, 144:169, 2007),
reviewed over 124 culture proven cases reported to USA eye centers between
2004-2006. The study employed the case controls from the Fusarium outbreak.
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 4/21
Protective Applications, LLC – D.G. Ahearn4
Original 9/12/07Rev. 12/16/07 (REC)D.G. Ahearn
Acanthamoeba keratitis
CDC noted in July 2007, a 16-fold greater risk of AK associated with the use of
Complete MoisturePlus (CMP) versus other multipurpose solutions. The CMP
solution, as marketed, has not been found to be contaminated (culture positive)
with Acanthamoeba . CMP, as a fresh solution, was nominally inhibitory for
common contact lens case contaminants relative to other MPS in several reports.
When CMP became contaminated in the contact lens case under the stress of
consumer use with poor hygienic practices, chance exposure to cysts or
trophozoites of Acanthamoeba from shower or drain aerosols has been proffered
to result in their amplification. Certain environmental stresses such as addition of
fresh CMP to the case (“topping off”) may induce trophozoites to rapid cyst
formation relative to that observed with other MPS. Studies by Kilvington et al (Eye
& contact Lens. 2008;34:133-139) indicate that this phenomenon is related to the
interaction of the propylene glycol content of the formulation.
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 5/21
Protective Applications, LLC – D.G. Ahearn5
Original 9/12/07Rev. 12/16/07 (REC)D.G. Ahearn
Acanthamoeba keratitis
Repeated “topping off” followed by evaporation and occasional rinsing of the case
with water, may enhance densities and survival of amoebic cysts in the MPS and
its drying residue. Cysts may be sequestered and protected in the drying film
within cationic cellulose-propylene glycol complexes. Without a manual rubbing
step and with insufficient rinsing ( with fresh CMP or water), trophozoites and
especially cysts may be transferred from the contact lens case via the contact lens
to the eye, increasing the risk of infection. The lens type, strain and density and
form of infectious amoeba propagules, and host immune factors, may all play a
role in the possible development of rare chronic or acute keratitis. Cysts,
particularly, may be irritating to the eye and predispose the eye to a diseased-
state infection with trophozoites.
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 6/21
Protective Applications, LLC – D.G. Ahearn6
Original 9/12/07Rev. 12/16/07 (REC)D.G. Ahearn
Acanthamoeba keratitis
Rare AK, in general, is associated with contact lens wear but the low incidence of
the disease has discerned among the various MPS (to this date) only use of CMPas a risk factor. Stress conditions that potentiate various MPS (including CMP) to
contamination by Acanthamoeba are still ill-defined. Our preliminary observations,
however, suggest that MPS, in general, are subject to partitioning and phase
separation of inhibitory components upon evaporation. All MPS, if repeatedly driedin the contact lens storage case, leave residues that under rare conditions
harbor amoebae.
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 7/21
Protective Applications, LLC – D.G. Ahearn7
MPS may evaporate from a contact lens caseunder ambient conditions and leave a more orless, “dry” film.
Various MPS, as they dry, may produce non-inhibitory residues that support growth or harbormicroorganisms such as Fusarium spp. and
Acanthamoeba.
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 8/21
Protective Applications, LLC – D.G. Ahearn8
Dried Films of MPS
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 9/21
Protective Applications, LLC – D.G. Ahearn9
Findings at GSU & Emory - Surface Contamination
Outer surface and thread of lens case
ZHANG et al
2006
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 10/21
Protective Applications, LLC – D.G. Ahearn10
AMOComplete MoisturePlus
Bausch & LombReNu MultiPlus
AlconOpti-Free Express
CIBA VisionAquify
Drying MPS and Phase Separation ZHANG et al
2008
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 11/21
Protective Applications, LLC – D.G. Ahearn11
AMOComplete MoisturePlus
Bausch & LombReNu MultiPlus
AlconOpti-Free Express
CIBA VisionAquify
A
c a n t h a m o e b a
F u s a r i u m
D r y f i l m
Drying MPS and Phase SeparationMPS with distinctive residue patterns after 20-h evaporation microscopic crystals and
humetant morphologies without and with conidia of fusaria and cysts of amoeba.
ZHANG et al 2008
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 12/21
Protective Applications, LLC – D.G. Ahearn12
Mature cysts of Acanthamoeba are produced in
“dried MPS” at 12-20 h from inocula of about 105
trophozoites, but were most prominent in CMP anda PBS control.
Cysts often were formed in clusters apparentlydependent in part upon rate of drying and initialaggregation or dispersion of the trophozoites in
the particular MPS.
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 13/21
Protective Applications, LLC – D.G. Ahearn13
Cluster of mature cysts
The foreign body sensation reported by
Acanthamoeba keratitis patients may be due to thepresence of cysts. Inflammation caused by cystsmay potentiate recurrent trophozoite invasions of cornea tissue in chronic infections.
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 14/21
Protective Applications, LLC – D.G. Ahearn14
Cysts in dried CMP ZHANG et al 2008
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 15/21
Protective Applications, LLC – D.G. Ahearn15
Phase Separation – maybe related to Acanthamoeba keratitis?
Findings at GSU & Emory - Dry MPS on surfaces
ARVO 2008
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 16/21
Protective Applications, LLC – D.G. Ahearn16
The Presentation
At 2008 ARVO meetings in Florida.
S. Zhang, Ph.D.1
, D.G. Ahearn, Ph.D.1
, R.D. StultingMD, Ph.D. 2, and S.A. Crow, Ph.D. 1
1George State University, 2 Emory University
Preceding slides are an
extension of
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 17/21
Protective Applications, LLC – D.G. Ahearn17
“Established and speculative
aspects of rareAcanthamoeba keratitis”
Microbiological Testing for Contact Lens CareProducts Workshop – Jan 22, 2009
Acanthamoeba D.G. Ahearn
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 18/21
Protective Applications, LLC – D.G. Ahearn18
1. Repeated rinsing and air drying of a contact lenscase with any MPS results in the eventualdevelopment of residue deposits or a film on andin the contact lens case.
2. The MPS deposits on the case may vary in theiractivity towards microorganisms. Some regions of the film or deposits may support (selective!)microbial growth whereas other regions may beinhibitory.
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 19/21
Protective Applications, LLC – D.G. Ahearn19
3. Some of the trophozoites in concentrations (near
105 ml) introduced into fresh and drying MPSundergo lysis while others are induced to producecysts.
4. The number of cysts produced during the dryingperiod vary with the MPS formulation and degreeof drying.
5. Low densities of trophozoites (near 103/ml in currently marketed MPS ) or cysts (near 100/ mlof MPS) do not yield readily recoverabletrophozoites from their 24-48 h dried films. Thevolume of MPS dried (one or two ml) and rate of drying can make a difference in recoveries.
8/3/2019 Presentation Ahearn
http://slidepdf.com/reader/full/presentation-ahearn 20/21
Protective Applications, LLC – D.G. Ahearn20
6. The MPS deposits may harbor cysts of
Acanthamoeba (and sometimes trophozoites) overextended periods, either forming a protective andbinding coating or by their hydroscopic nature.The cysts may not be easily rinsed from the
storage case.
7. Recommendation: Clean case with a mild detergent
and hot water with a thorough rinse and air dry.With precaution warnings, an additional rinse withnon-stabilized H2O2 may be instituted. Alternately,a single rinse and air drying step with the MPS
following the cleaning step may be applied. Astandard replacement of the contact lens case isrecommended.