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

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 Clinicas 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.