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

Correlation of central corneal thickness and associated factors in premature infants with and without retinopathy of prematurity

OBJECTIVE

Central corneal thickness (CCT) in premature infants is described in racially homogenous populations, and factors affecting CCT in infants are relatively unknown. This study describes CCT in premature infants and its association of steroid and oxygen requirements, gestational age (GA), birth weight (BW), race, and their relationship with CCT and corneal haze.

METHODS

CCT measurements of 87 infants/174 eyes screened for retinopathy of prematurity were taken between 30 and 44 weeks of GA. CCT was analyzed using a mixed model for its relationship with BW, GA, race, corneal clarity, steroid, and oxygen use.

RESULTS

Average CCT decreased at a rate of 12.3 μm/week. Caucasians had the thickest corneas and Hispanics the thinnest (p < 0.01) at baseline, but the rate of CCT decline varied based on racial/ethnic group (p = 0.079). Infants with BW <1000 g had a higher CCT at baseline, but CCT decreased at a faster rate than infants with higher BW (-13. 4 μm/week vs -9.9 μm/week, p = 0.020). Infants born <27 weeks of GA had higher CCT at baseline, but CCT decreased at faster rate compared with patients born later (-13.3 μm/week vs -10.1 μm/week, p = 0.029). Steroid and oxygen use were not statistically significantly associated with CCT or corneal haze (p > 0.05) CONCLUSIONS: CCT varies by racial group in premature infants. Lower BW and GA are associated with increased CCT at baseline but thin at a faster rate. Average, CCT decreases at a rate of 12.3 μm/week between 30 and 44 weeks GA and averages to 550 μm by 44 weeks GA.

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.

The Effect of Laser Photocoagulation on Intraocular Pressure in Premature Infants With Retinopathy of Prematurity

PURPOSE

To evaluate the effects of diode laser treatment on intraocular pressure (IOP) of premature infants with retinopathy of prematurity (ROP).

PATIENTS AND METHODS

The premature infants who underwent retinal laser photocoagulation therapy for ROP, and gestational age-matched, birth weight-matched, and sex-matched premature infants with ROP which recovered spontaneously without any treatment were enrolled into the study. Anterior segment examination and longitudinal IOP and central corneal thickness measurements were performed 5 times as follows: 1 day before the laser treatment (T0), and 24 hours (T1), 1 week (T2), 1 month (T3), and 3 months (T4) after the laser treatment. Premature infants who experienced any complication related to the laser treatment were excluded from the study.

RESULTS

Laser treated 67 premature infants and 70 premature infants in control group met inclusion criteria. Significant linear decreases in IOP and central corneal thickness values were measured throughout the study period for both groups (both, P<0.001). These changes were similar in 2 groups. There was a statistically insignificantly (P=0.999) and transient increase in the mean IOP value in the laser-treated group 24 hours after laser treatment. None of the patients in the laser-treated group experienced a shallow anterior chamber or a remarkable IOP elevation.

CONCLUSIONS

Diode laser treatment for ROP was safe, and did not raise the IOP of premature infants.