Changes in Corneal Detection Thresholds After Repeated Tear Film Instability

Area of Science:

• Ophthalmology
• Neuroscience
• Sensory Science

Background:

• Tear film instability is a common issue, particularly in dry eye disease.
• Repeated disruption of the tear film may impact corneal sensitivity.
• Understanding these effects is crucial for managing ocular discomfort.

Purpose of the Study:

• To investigate the impact of repeated tear film instability on corneal sensory detection thresholds.
• To use a human model to simulate tear film disruption and assess its consequences.
• To evaluate changes in cold, mechanical, and chemical detection thresholds.

Main Methods:

• Twenty-five subjects underwent three study visits.
• Corneal detection thresholds were measured using a Belmonte esthesiometer before and after sustained tear exposure (STARE) trials.
• Ocular discomfort and tear film changes were assessed during and after STARE.

Main Results:

• Repeated STARE trials significantly increased ocular discomfort symptoms.
• Tear breakup occurred in all trials, affecting 25-88% of the corneal area.
• Mechanical sensory thresholds were significantly altered 30 minutes after STARE, but cold and chemical thresholds were not.

Conclusions:

• Repeated tear film instability leads to increased ocular discomfort and altered mechanical sensitivity.
• These findings suggest that tear film instability during normal blinking could cause neurosensory alterations in dry eye patients.
• The study highlights a potential mechanism for chronic discomfort in individuals with dry eye disease.