Tear flow and soft contact lenses

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Physiology

Background:

• Tear film dynamics are crucial for ocular surface health and contact lens comfort.
• Understanding tear flow alterations with soft contact lens wear is essential for improving lens design and patient outcomes.

Purpose of the Study:

• To investigate the impact of soft contact lens adaptation on human tear flow.
• To characterize tear clearance mechanisms with and without soft contact lenses.

Main Methods:

• Utilized a radioactive tracer (technetium, Tc99m) and gamma camera imaging to quantify tear flow.
• Measured tear elimination rates in participants before and after one month of soft contact lens wear.
• Assessed tear clearance with pre-soaked and non-pre-soaked soft contact lenses.

Main Results:

• Soft contact lens adaptation led to a significant increase in the fractional turnover rate during the rapid elimination phase of tear flow.
• No significant change was observed in the slower, basal tear elimination phase.
• Tear elimination curves became monophasic when soft contact lenses were in place, differing from normal diphasic tear flow.

Conclusions:

• Soft contact lens wear significantly modifies tear film turnover, primarily affecting the rapid clearance phase.
• The presence of a soft contact lens alters the normal diphasic tear elimination pattern to a monophasic system.
• These findings provide insights into the physiological changes occurring with soft contact lens use.