Development of tearing in preterm and term neonates.
BACKGROUND
Although term and preterm infants have the capacity to secrete tears, the relative contribution of basal and reflex secretion of tears has not been previously assessed together in a prospective study. This information potentially has practical clinical importance.


OBJECTIVE
To measure basal and reflex tear secretion in preterm (30-37 weeks after conception) and term (38-42 weeks) newborns and to determine the developmental pattern of tear production.


METHODS
Tear secretion was evaluated by applying Schirmer tear test strips to the inferior fornix for 5 minutes before (reflex plus basal secretion) and after (basal secretion) applying a topical anesthetic agent.


RESULTS
Seventy infants (36 preterm and 34 term) were tested. Mean (+/- SD) basal tear secretion was 6.2 (+/- 4.5) mm in preterm and 9.2 (+/- 4.3) mm in term infants and increased progressively with increasing weight (P<.001) for all newborns. Mean (+/- SD) reflex tear secretion was 7.4 (+/- 4.8) mm in preterm and 13.2 (+/- 6.5) mm in term infants and also increased with increasing weight (P<.001) for all newborns.


CONCLUSIONS
Preterm infants have reduced reflex and basal tear secretion. This may mask the diagnosis of a nasolacrimal duct obstruction, concentrate topically applied medications, and allow corneas to quickly become dry during ophthalmological examination and treatment. By term, tear production in newborns is similar to that in adults.
Isenberg
S J
SJ
Jules Stein Eye Institute, Department of Ophthalmology, Harbor-University of California-Los Angeles Medical Center, Torrance 90509, USA. isenberg@ucla.edu
Apt
L
L
McCarty
J
J
Cooper
L L
LL
Lim
L
L
Del Signore
M
M
D003941:Diagnostic Techniques, Ophthalmological; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn / Q000378:metabolism*; D007234:Infant, Premature / Q000378:metabolism*; D007767:Lacrimal Duct Obstruction / Q000175:diagnosis / Q000378:metabolism; D011446:Prospective Studies; D013666:Tears / Q000378:metabolism*