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Effect of lid closure on contact lens-associated Pseudomonas keratitis
1Department of Ophthalmology, Tufts-New England Medical Center, Boston, Mass. 02111.
Abstract:
New or used extended-wear soft contact lenses, preincubated in suspensions of Pseudomonas aeruginosa, were placed on the corneas of rabbits. The lids were then sutured shut for either 1 or 2 weeks. Bacterial keratitis occurred in 9 of 9 eyes fitted with the used contaminated lenses but in none of 12 eyes fitted with new contaminated or new noncontaminated lenses. Similar experiments were carried out with other lenses specifically designed to fit the cornea of rabbits. Some of these lenses were preworn by rabbits for 1 week (used), whereas others were new. A significantly greater incidence of bacterial keratitis was found in eyes that had undergone lid closure after the placement of used contaminated lenses (4 of 5) than in closed eyes with new contaminated lenses (1 of 8) and in open eyes with used contaminated lenses (0 of 13). These findings suggest that extended eyelid closure is a risk factor in the experimental model and may be a factor in clinical Pseudomonas keratitis associated with the wearing of extended-wear soft contact lenses.
Insights
Used extended-wear soft contact lenses, especially with closed eyelids, significantly increase the risk of bacterial keratitis in rabbits. New lenses, even when contaminated, did not cause infection, highlighting lens condition and eyelid closure as critical factors.
Area of Science:
- Ophthalmology
- Microbiology
- Medical Devices
Background:
- Extended-wear soft contact lenses are associated with microbial keratitis.
- Pseudomonas aeruginosa is a common pathogen in contact lens-related infections.
Purpose of the Study:
- To investigate the role of used versus new extended-wear soft contact lenses in developing bacterial keratitis.
- To evaluate the impact of eyelid closure on infection risk in an experimental rabbit model.
Main Methods:
- Rabbits' corneas were fitted with new or used soft contact lenses contaminated with Pseudomonas aeruginosa.
- Eyelids were sutured shut for 1-2 weeks, or left open for comparison.
- Infection incidence was recorded for different lens and eyelid conditions.
Main Results:
- Used, contaminated lenses with sutured eyelids resulted in bacterial keratitis in all infected eyes (9/9).
- New contaminated or new non-contaminated lenses did not cause keratitis.
- Used contaminated lenses with lid closure showed a higher infection rate (4/5) than new contaminated lenses (1/8) or open eyes with used lenses (0/13).
Conclusions:
- Used extended-wear soft contact lenses are a significant risk factor for Pseudomonas keratitis in this rabbit model.
- Extended eyelid closure exacerbates the risk of infection when using contaminated, used lenses.
- Findings suggest lens age and eyelid closure are critical factors in clinical Pseudomonas keratitis associated with extended-wear contact lenses.