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Temporal sequence of changes in tear film composition during sleep
K O Tan1, R A Sack, B A Holden
1Cooperative Research Centre for Eye Research and Technology, School of Optometry, University of New South Wales, Sydney, Australia.
Current Eye Research
|November 1, 1993
Summary
Overnight eye closure causes sub-clinical inflammation in the tear film, marked by increased albumin, secretory IgA (sIgA), and polymorphonuclear (PMN) cells. These inflammatory markers appear before PMN cell recruitment after 3-5 hours of sleep.
Area of Science:
- Ophthalmology
- Immunology
- Cell Biology
Background:
- Overnight eye closure alters tear film composition, shifting from reflex tears to a stagnant, secretory IgA (sIgA)-rich layer.
- This change is associated with sub-clinical inflammation, indicated by elevated albumin, plasminogen activation, complement C3 conversion, and polymorphonuclear (PMN) cell presence.
Purpose of the Study:
- To investigate the temporal sequence and functional links between tear film composition changes and inflammatory responses during sleep.
- To quantify the time course of inflammatory markers and cell recruitment in the precorneal tear film.
Main Methods:
- Tear samples were collected from non-contact lens wearers after 1, 2, 3, 5, and 8 hours of sleep.
- Analyses included quantitative immunofixation for albumin, radial immunodiffusion for sIgA, chromogenic substrate assay for plasmin-like activity, and immunoblot assay for complement C3 conversion.
- Corneal washings were analyzed for epithelial and PMN cell counts.
Main Results:
- Epithelial cell accumulation increased progressively with sleep duration.
- PMN cell concentration showed a lag phase, with recruitment occurring between 3 and 5 hours of eye closure.
- Plasminogen activation, increased albumin and sIgA, and complement C3 conversion preceded PMN recruitment, occurring within 1-3 hours of eye closure. Plasmin-like activity peaked at 3 hours.
Conclusions:
- Sleep-induced eye closure initiates a cascade of inflammatory events in the tear film.
- The observed sequence suggests that changes in tear film composition and early inflammatory markers precede the significant influx of PMN cells.