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Corneal stress test for extended wear
1School of Medicine, Case-Western Reserve University, Cleveland, OH, USA.
Summary
Corneal swelling after one night of overnight contact lens wear can predict which eyes are at risk for infection. A swelling of 5% or less indicates tolerance for extended wear.
Area of Science:
- Ophthalmology
- Corneal Physiology
- Contact Lens Research
Background:
- Overnight contact lens wear is linked to infectious corneal ulcers.
- Corneal hypoxia during sleep is a suspected predisposing factor.
Purpose of the Study:
- To develop a test identifying corneas susceptible to oxygen deprivation during extended wear.
- To assess corneal swelling as a risk indicator for overnight contact lens wear complications.
Main Methods:
- Measured baseline corneal thickness in 161 eyes.
- Refitted soft lenses and repeated pachymetry after one night of wear.
- Instructed patients to continue wear for six additional nights.
Main Results:
- 17 of 161 eyes failed due to corneal decompensation.
- No failures occurred in eyes with <=5% swelling after one day.
- Eyes with >13% swelling all failed; 50% failure rate for 6-13% swelling.
- Thicker hyperopic lenses correlated with higher failure rates.
Conclusions:
- Corneal swelling after one night of wear can identify corneas at risk for oxygen deprivation.
- Corneal swelling of 5% or less suggests tolerance for 7 nights of extended wear (P < 0.001).