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Measurement of difference thresholds on the ocular surface.
Subam Basuthkar Sundar Rao1, Trefford L Simpson
1School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.
Investigative Ophthalmology & Visual Science
|January 16, 2014
Summary
Contact lens wearers exhibit altered corneal mechanical sensitivity compared to non-wearers. This study measured corneal difference thresholds (DLs) using a pneumatic esthesiometer, revealing subtle differences in sensory processing between the groups.
Area of Science:
- Ophthalmology
- Neuroscience
- Sensory Physiology
Background:
- The cornea's mechanical sensitivity is crucial for ocular surface health and protective reflexes.
- Understanding corneal sensory processing differences between contact lens wearers and non-wearers is important for identifying potential risks and improving lens design.
Purpose of the Study:
- To establish difference thresholds (DLs) of the central cornea.
- To compare corneal mechanical sensitivity between contact lens wearers and non-wearers.
Main Methods:
- Mechanical sensitivity was assessed using a modified Belmonte pneumatic esthesiometer and method of limits.
- Difference thresholds (DLs) were measured in 12 lens wearers and 12 non-wearers.
- Weber's constants were calculated and compared between groups using repeated-measures ANOVA.
Main Results:
- A significant effect of DL level on Weber's constant was observed (P < 0.001).
- Contact lens wearers demonstrated higher Weber's constants than non-wearers (P = 0.02).
- No significant interaction was found between DL level and group type (P = 0.38).
Conclusions:
- Differential sensitivity of the ocular surface can be reliably measured with a pneumatic esthesiometer.
- Corneal sensory processing appears to follow Weber's law.
- Subtle differences in corneal mechanical thresholds suggest altered neural activity in contact lens wearers.
