Development of Tearing in Preterm and Term Neonates

MUC5AC overexpression in tear film of neonates

“…This characteristic explains the capability of neonates to have a reduced blink rate without the risk of developing dry eye [23]: in fact, tear-film stability is based not only on the integrity of the lipid layer but also on the adhesion of molecules to the underlying epithelium [13,19]. We also report that reflex tear secretion is present in neonates already in the first days of life, and we obtained results consistent with those previously reported in literature for neonates in the first weeks of life [3,7,16,20]: the amount of tears we collected was greater in adult controls than in neonates, suggesting that a greater tear-film stability in early life may play a major role in preventing drying of the ocular surface caused by evaporation of the tear film during long interblink periods. In fact, our finding of a low blink rate and long interblink time in neonates was also consistent with previous literature; however, although we did not compare our findings directly with children of other age-groups, we report an even lower mean blink rate and interblink time in neonates in the first days of life as compared to older neonates enrolled in previous studies, suggesting that development of blinking is a continuous process that starts with birth and continues until complete maturation [10].…”

“…Most of the previous studies on the characteristics of the tear film of infants looked at the overall secretion of tears or at the characteristics of the aqueous and lipid layers [7], but no studies have yet been focused on the tear-film mucus layer.…”

Formulations for children: problems and solutions

“…The eye of the newborn is roughly two thirds of its adult size, reaching an adult size around ages 3 to 4 years [80]. In the eye, membranes are thin in neonates and infants, so drug absorption and corneal permeation may be more rapid in these groups [81,82].…”

Eye blink in newborn and preschool-age children

“…In addition, a reduced rate of reflex tear secretion may limit the dilution of topical ocular medication, leading to a longer period of contact between the drug and the ocular surface and thus increasing the risk of adverse reactions (Isenberg et al 1998).…”

“…The lipid layer of tear film in newborn infants is thicker than in adults, slowing evaporation and increasing tear film stability, and thus preventing ocular surface drying (Isenberg et al 1998;Lawrenson et al 2005). In addition, less ocular surface area is exposed in newborn infants (Fox 1966).…”