Risk factors for contact lens bacterial contamination during continuous wear.
OBJECTIVE
Microbial contamination of contact lenses is associated with corneal infection and inflammation. This study determined the microbiological, clinical, and demographic factors that are associated with bacterial contamination of a silicone hydrogel contact lens when worn for continuous wear (CW).


METHODS
Two hundred five healthy subjects were enrolled in the Longitudinal Analysis of Silicone Hydrogel Contact Lens Study and were fitted with lotrafilcon A lenses for monthly CW and followed for 1 year. Lenses were aseptically removed after 1 week and 4 months of wear and cultured using an agar sandwich technique. Lids and conjunctiva were routinely cultured at baseline and after 1 week and 4 months of CW. Lenses and ocular sites were considered to have substantial microbial bioburden when they harbored pathogenic organisms or high levels of commensal organisms. Univariate and multivariate logistic regression analyses were conducted to examine whether substantial conjunctival or lid bioburden, subject demographics, lens-wearing history, symptoms, and biomicroscopic signs were associated with lens bioburden.


RESULTS
About one third (32.4%) of subjects had substantial bacterial bioburden in either eye across multiple visits. Over half (53.2%) and about one tenth (11.7%) of subjects had substantial lid and conjunctival bioburden, respectively, and 11.2% discontinued because of discomfort. The adjusted odds ratios (and 95% confidence intervals) for presence of substantial lens bioburden were 2.49 (1.17-5.30), 4.24 (1.45-12.40), and 4.11 (1.17-14.46) for substantial lid bioburden, substantial conjunctival bioburden, and lens discomfort, respectively.


CONCLUSIONS
Bacterial contamination of silicone hydrogel contact lenses is common during CW. Substantial lens bioburden is associated with discomfort precluding successful CW. The presence of substantial lid and conjunctival bioburden is associated with a 2.5-fold and more than fourfold greater risk of substantial lens bioburden and is likely the major route of contamination.
Department of Ophthalmology & Visual Sciences, Case Western Reserve University, Cleveland, Ohio 44106, USA. loretta.szczotka@uhhospitals.org
Loretta B
LB
Szczotka-Flynn
Saralee
S
Bajaksouzian
Michael R
MR
Jacobs
Alfred
A
Rimm
D000293:Adolescent; D000328:Adult; D001419:Bacteria / Q000302:isolation & purification*; D015331:Cohort Studies; D015169:Colony Count, Microbial; D003228:Conjunctiva / Q000382:microbiology; D003262:Contact Lenses, Extended-Wear / Q000382:microbiology*; D003263:Contact Lenses, Hydrophilic / Q000382:microbiology*; D004866:Equipment Contamination; D005143:Eyelids / Q000382:microbiology; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D020100:Hydrogels; D008137:Longitudinal Studies; D008875:Middle Aged; D015999:Multivariate Analysis; D009819:Office Visits; D011446:Prospective Studies; D012307:Risk Factors; D012828:Silicones; D055815:Young Adult; D005466:Fluorocarbons
D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D020100:Hydrogels; D012828:Silicones; C481129:lotrafilcon A; D005466:Fluorocarbons