Regional Tear Film Quality Changes Across Eye Gaze Directions Revealed by Spatial Mapping and Threshold Sensitivity...

Area of Science:

• Ophthalmology
• Optometry
• Vision Science

Background:

• Tear-film quality is crucial for clear vision and ocular comfort.
• Previous studies often analyzed tear-film quality using global measures, potentially overlooking regional variations.
• Eccentric gaze (looking away from straight ahead) may influence tear-film distribution due to lid and ocular surface changes.

Purpose of the Study:

• To investigate if eccentric gaze causes a regional, gaze-aligned redistribution of tear-film quality.
• To determine if spatial analysis reveals this redistribution more effectively than whole-map summary measures.
• To analyze tear-film quality changes across different gaze directions (ahead, right, left, up, down).

Main Methods:

• Secondary analysis of a Medmont Meridia topography dataset from 38 healthy participants.
• Tear-film quality maps were generated for five gaze directions and aligned to a common reference frame.
• Analysis included global measures, regional spatial mapping, and threshold-based directional sector analysis (threshold 0.35).

Main Results:

• Global tear-film summary measures showed minimal variation with gaze direction.
• Spatial mapping revealed systematic regional redistribution of tear-film quality during eccentric gaze.
• Gaze-aligned sector indices were significantly positive for right, left, up, and down gaze compared to ahead gaze (p<0.001).

Conclusions:

• Tear-film quality exhibits regional variations dependent on gaze direction.
• Spatial mapping and sector analysis are superior to global summaries for detecting these gaze-aligned patterns.
• Ocular surface topography measurements during straight-ahead gaze may not fully represent tear-film behavior in eccentric viewing conditions.