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Buffering in human tears: pH responses to acid and base challenge
L G Carney1, T F Mauger, R M Hill
1College of Optometry, Ohio State University, Columbus 43210.
Investigative Ophthalmology & Visual Science
|April 1, 1989
Summary
Tear fluid buffering capacity varies between individuals, with stronger buffering observed during acid titration. This study analyzed tear pH and buffering components in healthy subjects.
Area of Science:
- Ophthalmology
- Physiological Chemistry
Background:
- Tear fluid plays a crucial role in maintaining ocular surface health.
- Understanding the buffering capacity of tears is essential for ocular physiology and pharmacology.
Purpose of the Study:
- To assess the buffering capacity of human tear fluid across the pH spectrum.
- To identify variations in buffering capacity among healthy individuals.
Main Methods:
- Microtitration technique used to determine tear buffering capacity in six healthy subjects.
- Tear samples collected over several hours with minimal stimulation.
- pH measurements performed using a microelectrode chamber at a stabilized temperature of 36°C.
- Comparative analysis with degassed, demineralized distilled water.
Main Results:
- Significant intersubject variations in tear buffering capacity were observed.
- Buffering capacity was more pronounced and uniform following acid titration compared to base titration.
- Specific pH ranges with enhanced buffering were identified, suggesting multiple buffering components.
Conclusions:
- Human tear fluid exhibits variable buffering capacity influenced by individual differences.
- The bicarbonate and protein content likely contribute significantly to the observed buffering effects.
- These findings have implications for understanding tear film stability and ocular drug delivery.