Intraocular pressure in very low birth weight preterm infants and its association with postconceptional age

Abstract

OBJECTIVE:To evaluate intraocular pressure in very low birth weight preterm infants and correlate it with postconceptional age.METHODS:The intraocular pressure in a prospective cohort of very low birth weight premature infants (defined as a birth weight ≤1,500 g and gestational age ≤32 weeks) admitted to Hospital de Clínicas de Porto Alegre, Brazil was evaluated weekly. The evaluated outcome was the variation in the intraocular pressure following changes in the postconceptional age (defined as the gestational age at birth plus the age in weeks at the time of examination) in the weeks following preterm birth. Mixed-effects models were used for the statistical analysis to determine the intraocular pressure variation according to postconceptional age, and means and 10th and 90th percentiles were calculated for the intraocular pressure values.RESULTS:Fifty preterm infants with a mean gestational age of 29.7±1.6 weeks and a mean birth weight of 1,127.7±222.7 g were evaluated. The mean intraocular pressure for the entire cohort considering both eyes was 14.9±4.5 mmHg, and 13.5% of all recorded intraocular pressure values were greater than 20 mmHg. The analysis revealed a mean reduction in the intraocular pressure of 0.29 mmHg for each increase in postconceptional age (p = 0.047; 95% CI: −0.58 to −0.0035). The mean intraocular pressure (P10–P90) decreased from 16.3 mmHg (10.52–22.16) at 26.3 weeks to 13.1 mmHg (7.28–18.92) at 37.6 weeks of postconceptional age.CONCLUSIONS:The mean intraocular pressure in very low birth weight preterm infants was 14.9±4.5 mmHg. This value decreased 0.29 mmHg per week as the postconceptional age increased.

Longitudinal assessment of intraocular pressure in premature infants

“…Measurements after 34 weeks PCA indicate that decline trend slows down approaching the term period. The decline in IOP as PCA increases is also in good agreement and corresponds closely with values obtained from the previous longitudinal studies (13)(14)(15)(16). It is probable that the decline in IOP as PCA increases might be a result of maturation of the aqueous drainage system.…”

“…Therefore, we excluded infants with systemic problems to minimize the effects of systemic factors on IOP. Fourth, the previous longitudinal studies reported IOP values in subjects with wider PCA ranges than in our study (13)(14)(15). In the present study, all infants were at 26 weeks of GA, thus, in a homogeneous group, we assumed that our results may better reflect the natural course of IOP in the following weeks after premature birth.…”

“…In the present study, all infants were at 26 weeks of GA, thus, in a homogeneous group, we assumed that our results may better reflect the natural course of IOP in the following weeks after premature birth. Additionally, in the present study, IOP measurements were taken at early stages of postnatal life with more IOP measurements when compared with previous longitudinal studies ( [13][14][15][16]. All measurements were performed by the same ophthalmologist within a limited time frame (4:30 PM to 6:00 PM), minimizing the possibility of diurnal IOP variations.…”

“…Intraocular pressure levels in preterm infants are thought to be different from those in adults and full-term newborns. To date, various researchers have studied IOP values in premature infants (1-15). Several studies found higher IOP values; however, lower IOP measures were also reported.…”

“…Several studies found higher IOP values; however, lower IOP measures were also reported. Most of these studies were performed in a cross-sectional manner (1-10), and few longitudinal studies are available in the literature (13-16). In the present study, we aimed to investigate the longitudinal change in IOP in premature infants and to establish the normative IOP value.…”