Date of Award

Spring 8-1-2008

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Life Sciences

First Advisor

H. Kathleen Dannelly

Second Advisor

Mary Ann McLean

Third Advisor

Gary Stuart

Abstract

In March 2006, ophthalmologists noticed increased Fusarium keratitis in patients wearing soft contact lenses; the etiology was that of Fusarium solani. By May of 2006, CDC reported receiving a total of 130 confirmed cases of Fusarium keratitis across 26 states and one territory; of the 118 who could identify the lens solution they had used, 64% reported using Bausch & Lomb's ReNu with Moistureloc ©,while 18% reported using only non-Bausch & Lomb products. The association between Fusarium keratitis and ReNu with Moistureloc was not clear. Nevertheless, Bausch & Lomb withdrew Moistureloc solutions worldwide. In earlier laboratory tests using standard methods for Contact Lens solution testing, Fusarium solani populations were reduced sufficiently to meet FDA standards for ReNu solutions. So if a disinfectant is effective in the laboratory, why is it not effective when used for its intended purpose? To answer this question, contact lens solution efficiency was tested under the following conditions: 1.) after Fusarium solani is attached to the lenses, 2.) with various lens materials using Staphylococcus aureus, Pseudomonas aeruginosa and Fusarium solani, three known eye pathogens, and 3.) after incubation in various tube materials using the same three eye pathogens. It appeared that after Fusarium solani was attached to lenses, a contact lens solution was not effective; though more work is needed to devise a way to quantify living fungi bound to the lenses for comparison. Research performed to test contact lens solution efficiency against S. aureus, Fusarium solani, and P. aeruginosa showed that Renu products and Complete products are significantly less effective at killing the organisms than are Optifree and Clear Care products. In addition, pre-incubation of solutions with several of the lens materials and the plastic tube materials significantly affected the efficiency of the contact lens solutions. It seems that the manufacturers of contact lens solutions should perform additional testing to mimic real world conditions for use of their products. As many contact users know, lenses normally have proteins bound to them from the eyes. To assess this, serum was used to mimic the natural occurrence of protein and it appeared that more Fusarium binds to the lenses after pre-incubation with the proteins of serum. It is a possible that a biofilm is produced on lenses by Fusarium solani. Biofilms are known to be more resistant to killing by antimicrobial agents and this fact may play a role in the Fusarium outbreak of 2005-06. Further research to examine this aspect is needed.

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