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

Abstract

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