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Published on: February 23, 2018
Impact of air-drying lens cases in various locations and positions
Yvonne T Wu1, Hua Zhu, Mark Willcox
1Institute for Eye Research, University of New South Wales, Sydney, New South Wales, Australia.
Purpose:
To determine the rate and type of microbial contamination when contact lens cases are air-dried in two different positions (face up and face down) and in four different locations (toilet, bathroom, office, and bedroom).
Methods:
Unused contact lens cases (n = 97) were rinsed with 2-ml sterile phosphate buffered saline and then placed on facial tissue paper in different locations: humid (toilet and bathroom) and non-humid (office and bedroom) and air-dried at room temperature. After 24 h, the contact lens cases were collected and sampled for microbial numbers and microbial types identified using standard techniques. The microbial profile and the rate of contamination between different locations and positions were compared.
Results:
Irrespective of the air-drying location, contact lens cases positioned face up had a significantly higher contamination rate (34/48, 71%) compared with contact lens cases air-dried face down (6/49, 12%) (p < 0.001). For those contact lens cases air-dried face up, there was more contamination when placed in humid environments (toilet and bathroom) than in the non-humid environments (office and bedroom) (p = 0.01). However, the contact lens case contamination rate among various locations was similar when contact lens cases were air-dried face down. Total microorganisms recovered from contact lens cases ranged from 0 to 275 colony forming unit per well. The most frequently recovered microorganisms from the contaminated contact lens cases were coagulase-negative Staphylococci, fungi, and Bacillus spp. Thirty-three percent (13/40) of contact lens cases were contaminated with multiple species.
Conclusions:
Small numbers of microorganisms from the environment may contaminate contact lens cases while cases are air-dried face up. Cases air-dried in humid environments have higher levels of microbial contamination; this is particularly true when contact lens cases are positioned face up. On the basis of this limited study, we would recommend contact lens cases be air-dried face down.
Insights
Air-drying contact lens cases face up significantly increases microbial contamination, especially in humid areas. Drying cases face down is recommended to minimize contamination risk for contact lens wearers.
Area of Science:
- Microbiology
- Ophthalmology
- Infectious Diseases
Background:
- Contact lens cases are essential for contact lens hygiene.
- Improper case drying can lead to microbial contamination.
- Environmental factors may influence contamination rates.
Purpose of the Study:
- To investigate microbial contamination rates in contact lens cases.
- To compare contamination based on air-drying position (face up vs. face down).
- To assess the impact of drying location (humid vs. non-humid environments) on contamination.
Main Methods:
- 97 unused contact lens cases were air-dried for 24 hours.
- Cases were placed in four locations: toilet, bathroom, office, and bedroom.
- Cases were dried in two positions: face up and face down.
- Microbial contamination was quantified and identified using standard techniques.
Main Results:
- Face-up drying resulted in significantly higher contamination (71%) versus face-down drying (12%) (p < 0.001).
- Humid environments (toilet, bathroom) showed increased contamination for face-up cases (p = 0.01).
- Coagulase-negative Staphylococci, fungi, and Bacillus spp. were the most common contaminants.
- 33% of contaminated cases harbored multiple microbial species.
Conclusions:
- Air-drying contact lens cases face up increases microbial contamination.
- Humid environments exacerbate contamination, particularly when cases are face up.
- Recommends air-drying contact lens cases face down to reduce contamination.
