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Tear film volume and protein analysis in full-term newborn infants
M Esmaeelpour1, P O Watts, M E Boulton
1School of Optometry and Vision Sciences, Cardiff University, UK. esmaeelpourm@cf.ac.uk
Insights
Infant tear film volume and protein composition differ significantly from adults. This study provides the first investigation of unstimulated infant tears, revealing distinct tear protein profiles in newborns compared to adults.
Area of Science:
- Ophthalmology
- Neonatology
- Biochemistry
Background:
- The tear film is crucial for ocular surface health.
- Understanding infant tear film development is essential for diagnosing and managing neonatal eye conditions.
- Limited data exists on the protein composition of unstimulated infant tears.
Purpose of the Study:
- To investigate infant tear film secretion and protein profiles.
- To compare major tear proteins (immunoglobulin A, lactoferrin, lysozyme) in infants versus adults.
- To establish a baseline for infant tear film characteristics.
Main Methods:
- Noninvasive tear collection using cellulose rods from 40 healthy newborns and 14 infants at a later age.
- Tear samples were also collected from 22 adult controls.
- Tear volume was measured; protein content was analyzed via Bradford assay and gel electrophoresis.
Main Results:
- Infant tear volume significantly increased with age, remaining lower than adult tear volume (P < 0.001).
- Immunoglobulin A concentration was significantly lower in newborns (P < 0.001).
- While overall protein concentration was similar across age groups, specific protein presence differed, with lipocalin in 36% of newborns and serum albumin in 86%.
Conclusions:
- This is the first study to report on unstimulated infant tears using a noninvasive method.
- Infant tear protein content differs from that of adults, indicating unique physiological characteristics.
- Findings highlight developmental differences in the infant ocular surface.
Purpose:
To investigate infant tear film secretion and protein profile, and to compare major tear proteins, such as immunoglobulin A, lactoferrin, and lysozyme, with those of adult controls.
Methods:
Tears were collected, with a cellulose rod, from 40 healthy infants (19 female infants and 21 male infants, gestational duration: 39.71 ± 1.27 weeks) within 48 hours of birth and 22 adults (10 female infants and 12 male infants, mean age: 24.95 ± 3.63 years). A second collection was obtained from 14 of the infants (8 female infants and 6 male infants, postnatal age: 7.76 ± 6.14 weeks). The tear volume was measured, and protein in the samples was analyzed by Bradford assay and gel electrophoresis.
Results:
Median tear volume (interquartile range) was 0.5 μL (0.6-2 μL) for newborn infants, 2.5 μL (1.4-7.75 μL) for these infants at an older age, and 6 μL (2.73-12.75 μL) in adults (P < 0.001, Kruskall-Wallis test). Immunoglobulin A concentration was significantly lower in newborns (P < 0.001, analysis of variance). Lipocalin was present in 36% of the newborn tear samples, whereas serum albumin was found in 86%. Mean protein concentration (μg/μL ± SD) was 10.95 ± 5.51 in the newborns, 12.93 ± 3.99 in the older infants, and 13.04 ± 3.46 in the adults (P > 0.5, analysis of variance).
Conclusions:
This is the first study reporting an investigation of unstimulated infant tears, using a noninvasive collection method. Tear protein content demonstrated that the infant tear film is different to that in adults.
