Purpose: To evaluate the effect of the birth weight and the postconceptional age on the tear production of preterm and term newborn infants and to evaluate the changes in tear production during the first two months of life. SUBJECTS--METHODS: Both eyes of medically stable term and preterm infants were included in the study. Based on postconceptional age and birth weight, we divided preterm infants into three groups. Then, we measured the basal and reflex tear secretions of both eyes by Schirmer tests before and after instillation of topical anesthetic agent. We performed initial tear measurements on the second day of life (between first 24 hours to first 48 hours after birth): and at 2 weeks, 4 weeks and 8 weeks after birth.
Results: We tested a total of 138 infants (63 preterm and 75 term), 72 males and 66 females. Schirmer-1-test of preterm and terms on the 2nd day of life revealed a mean basal tear secretion (BTS) of 4.8 +/- 4.1 and 8.8 +/- 3.2 mm, respectively (p < 0.0001). The mean reflex tear secretion (RTS) within 48 hours of life was 6.1 +/- 3.9 mm and 10.3 +/- 4.4 mm in preterm and term infants, respectively (p < 0.0001). The mean values of both basal and reflex tear secretion were significantly lower in the preterm than the term infants during the first two months of the life. In preterm infants, both basal and reflex tear secretions were found to be highly correlated with postconceptional age (r: 0.79 and 0.74, respectively, both p values: 0.001); however, there was a weak correlation with birth weight (r: 0.16 and 0.19, respectively, both p values: 0.01). Statistically significant differences for both BTS and RTS existed among the three postconceptional age groups: there were no such difference among the three different birth weight groups. We found no gender or laterality dependent (side of the eyes) differences in the tear production (both p values >0.05).
Conclusions: Preterm infants have significantly reduced tear secretion compared with term infants. Postconceptional age, rather than birth weight, seems to be more correlated with the tear secretion. Sex and laterality does not appear to have an effect on tear production in infants. Tear production of preterm infants is significantly reduced than that of term infants during the first two months of life. Term infants increased their tear production significantly in each examination during the neonatal period while the preterms increase tear production significantly only at mean postconceptional age of eight and a half (8.5) months.