Onset and pattern of tear secretions in full-term neonates

Serial evaluations of total, basal and emotional tear secretion in full-term normal neonates to determine the time after birth when these parameters attain normal adult values.

Both eyes of 102 full-term normal neonates were prospectively evaluated for tear secretions in the Department of Ophthalmology, over a period of one year. Serial recording of the Schirmer I test (total tear secretions), Basal Secretion Test, and Schirmer II test (emotional tears) was done, the first one being within 6 hours of birth. All the tests were repeated in each infant until normal adult values for each test were obtained.

The average values of the Schirmer I test, Basal Secretion Test and Schirmer II test at birth were 23.2 (+/- 3.96) mm, 6.2 (+/- 2.15) mm and 19.2 (+/- 4.94) mm, respectively. A statistically significant correlation of birth weight but not of gestational age was found with basal secretions (p = 0.004) as well as with emotional tears (Schirmer II test, p = 0.010). At birth, 98% of infants had total tear secretion, 3.9% had basal tear secretion and 2.9% had emotional tear secretion comparable to normal adult values. All the parameters of tear secretions increased with time, so that 100% of infants had total tear secretion comparable to normal adult values within 12 hours of birth. The basal secretions took three weeks and emotional tears took four weeks to attain normal adult values in all the neonates.

Total tear secretions were the earliest to reach normal adult values, followed by basal secretions and, lastly, emotional tears. Reduced basal tears at birth may predispose neonates to corneal drying during prolonged ocular examinations such as indirect ophthalmoscopy and procedures under general anesthesia.