DEVELOPMENT OF TEARING IN PRETERM AND TERM NEONATES

Background: Although term and preterm infants have the capacity to sec rete tears, the relative contribution of basal and reflex secretion of tears has not been previously assessed together in a prospective stud y. This information potentially has practical clinical importance. Obj ectives: To measure basal and reflex tear secretion in preterm (30-37 weeks after conception) and term (38-42 weeks) newborns and to determi ne the developmental pattern of tear production. Methods: Tear secreti on 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 tea r secretion was 6.2 (+/- 4.5) mm in preterm and 9.2 (+/- 4.3) mm in te rm 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 increa sed with increasing weight (P<.001) for all newborns. Conclusions: Pre term infants have reduced reflex and basal tear secretion. This may ma sk the diagnosis of a nasolacrimal duct obstruction, concentrate topic ally applied medications, and allow corneas to quickly become dry duri ng ophthalmological examination and treatment. By term, tear productio n in newborns is similar to that in adults.