Determination of normal values of intraocular pressure and central corneal thickness in healthy premature infants—a prospective longitudinal study

Abstract Purpose To evaluate the longitudinal change of intraocular pressure (IOP) and central corneal thickness (CCT) in healthy premature infants. Methods Premature infants born at 28 weeks’ gestational age were included in this prospective, single-center longitudinal study. IOP was measured by handheld applanation tonometer (Tono-Pen Avia); CCT measurements were performed by ultrasonic pachymeter. Examinations were held at 32 weeks’ gestational age initially and at 2-week intervals thereafter for a total of 5 consecutive measurements by the same ophthalmologist. Results A total of 110 right eyes of 110 healthy premature infants were analyzed. The mean IOP at 32 weeks’ gestational age was 18.28 ± 2.78 mm Hg; mean CCT, 670.56 ± 55.72 μm. Mean IOP and CCT thereafter were 16.13 ± 2.20 mm Hg and 613.67 ± 48.11 μm in week 34, 14.67 ± 2.04 mm Hg and 579.24 ± 43.73 μm in week 36, 13.49 ± 2.08 mm Hg and 551.91 ± 40.75 μm in week 38, and 13.21 ± 1.94 mm Hg and 546.18 ± 38.70 μm in week 40. The longitudinal changes of mean IOP and CCT values between 5 consecutive measurements were statistically significant ( P < 0.001, for each). Conclusions IOP and CCT values decrease longitudinally in healthy premature infants between 32 and 40 weeks’ gestational age. Elevated IOP values, which were identified in the early premature period, seem to be associated with higher CCT values.