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The neonatal tear film
John G Lawrenson1, Paul J Murphy, Marieh Esmaeelpour
1Department of Optometry and Visual Science, City University, London, EC1V 0HB, UK.
Summary
Neonates have a tear film adapted to prevent ocular surface drying due to infrequent blinking. This tear film stability may impact the eye's defense against pathogens.
Area of Science:
- Ophthalmology
- Neonatal Physiology
- Ocular Surface Science
Background:
- The tear film is crucial for maintaining ocular surface integrity.
- Full-term neonates exhibit normal tear production but have low spontaneous blink rates.
- This raises questions about tear dynamics and stability in early life.
Purpose of the Study:
- To investigate the adaptations of the neonatal tear film.
- To understand how tear film stability is maintained despite low blink rates.
- To explore the implications of neonatal tear dynamics for ocular defense.
Main Methods:
- The study reviews existing evidence on neonatal tear film physiology.
- It considers the development of neural pathways for tear break-up detection.
- Indirect evidence regarding tear film composition and evaporation resistance is analyzed.
Main Results:
- Neonatal tear film appears adapted to resist evaporation, preventing ocular surface drying during prolonged inter-blink intervals.
- An afferent neural pathway for tear break-up detection is present at birth.
- Low tear turnover rates are suggested by the observed adaptations.
Conclusions:
- The neonatal ocular surface is protected from drying through tear film adaptations.
- Low tear turnover may compromise the neonatal eye's defense against pathogens.
- Further research is needed to fully elucidate neonatal tear film dynamics and defense mechanisms.