Improved technique for storage of tear microvolumes

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Analytical Chemistry

Background:

• Accurate osmolality measurement is crucial for diagnosing ocular surface diseases.
• Traditional methods for storing small tear volumes face challenges with evaporation and sample degradation.
• Existing storage techniques limit sample volume and duration, impacting clinical utility.

Purpose of the Study:

• To develop an improved, reliable method for storing microvolume fluid samples, specifically tear fluid, before osmolality measurement.
• To enhance the stability and integrity of small-volume samples to extend their usability for diagnostic testing.
• To optimize sample handling protocols for microfluidic applications in clinical diagnostics.

Main Methods:

• Utilizing capillary tubes containing Cargilles B immersion oil to store fluid microvolumes.
• Implementing Parafilm to seal the open end of the capillary tubes, preventing evaporation.
• Investigating the effect of water-saturated immersion oil on sample stability for smaller volumes.

Main Results:

• Reliable storage of 0.5-microliter tear samples was achieved for up to 24 hours using Parafilm-sealed capillary tubes.
• Storage of 0.1-microliter tear samples was reliably achieved for up to 18 hours when using water-saturated immersion oil and Parafilm sealing.
• The improved technique significantly enhances the viability of microvolume tear samples for subsequent osmolality analysis.

Conclusions:

• Parafilm sealing offers a simple and effective method for preserving microvolume fluid samples.
• The optimized storage technique supports the reliable measurement of tear osmolality from small sample volumes.
• This advancement has the potential to improve the diagnosis and management of dry eye disease and other ocular conditions.