Longitudinal assessment of intraocular pressure in premature infants

Purpose: To investigate the longitudinal change in intraocular pressure (IOP) in premature infants and to establish a normative IOP value. Methods: Forty premature infants with a gestational age (GA) of 26 weeks were enrolled in this longitudinal study. Measurements were taken initially at 28 weeks postconceptional age (PCA) and at 2-week intervals up to 40 weeks PCA. Intraocular pressure was measured with a hand-held tonometer (Tono-Pen XL; Reichert Inc.). Results: From 40 (22 male, 18 female) premature Caucasian infants, seven (for each eye) IOP measurements were obtained. Mean GA was 26 weeks and mean birthweight was 820 ± 112 grams. The mean IOP was 15.1 ± 1.2 mm Hg and 14.9 ± 1.1 mm Hg for the right and left eyes, respectively. The mean IOP in both eyes for all measurements was 15.0 ± 1.1 mm Hg. At 28 weeks PCA, 9 (22.5%) preterm infants had IOP values greater than 20 mm Hg. The mean IOPs at 28 weeks, 30 weeks, 32 weeks, 34 weeks, 36 weeks, 38 weeks, and 40 weeks PCA were 18.7 ± 1.1 mm Hg, 16.9 ± 0.9 mm Hg, 15.3 ± 0.9 mm Hg, 14.1 ± 1.3 mm Hg, 13.7 ± 1.3 mm Hg, 13.4 ± 1.4 mm Hg, and 13.1 ± 1.3 mm Hg, respectively. A significant decrease in IOP measurements was found up to 34 weeks PCA, with no significant decline in IOP measurements after that point (F = 109.7, p<0.01). There was a negative correlation between IOP and PCA (r = ?0.712, p<0.01). Conclusions: The mean IOP of premature infants was 15.0 ± 1.1 mm Hg and IOP values decreased significantly up to 34 weeks PCA, indicating a decline trend approaching the term period.