In comparison to the extensive amount of research on retinopathy of prematurity (ROP), there is limited literature on corneal thickness and haze in premature infants. Hence, in this issue, Islam and colleagues seek to contribute to the current body of literature by investigating: 1) central corneal thickness (CCT) and its rate of decline, and 2) CCT's association with systemic features—gestational age (GA), birth weight (BW), race, oxygen requirements, and steroid use—in a racially diverse population of premature infants in the United States.
- Islam Y
- Xue W
- Agarwal-Sinha S.
Correlation of central corneal thickness and associated factors in premature infants with and without retinopathy of prematurity.
Islam's group prospectively collected the data from 87 premature infants (174 eyes) at a single academic centre between 2018 and 2019. ROP screening was performed for all study participants. CCT was measured weekly or biweekly, starting at 30 weeks of GA or later until 44 weeks of GA. Multiple longitudinal analyses/ mixed model were performed to determine the association of CCT with GA, BW, race, corneal clarity, oxygen requirements, and steroid use.
To summarize the study's findings, CCT decreased from baseline (mean 744.8um) to the end of the study (547.1um) at an average of 12.3um/ week. With regards to analyses of CCT's associations with systemic features, first, infants born before 27 weeks of GA had a higher CCT at baseline (mean 717.0um vs 682.4um, p=0.036), and had a faster rate of decrease (13.3um/ week vs. 10.1um/ week, p=0.029) compared to those born at a later GA. Second, infants with a BW <1000g had higher CCTs at baseline (mean 723.2um vs. 674.5um, p=0.002) and had a faster rate of decrease (13.4um/ week vs. 9.9um/ week, p=0.020) compared to those with a BW 1000g. Third, Caucasian infants had the thickest corneas while Hispanics had the thinnest corneas; African American and Hispanic infants had slower rate of decrease in CCT compared to the Caucasian infants. Fourth, presence of corneal haze was positively correlated with thicker corneas (738um vs. 682.3um, p=0.002). Lastly, oxygen requirements and steroid use were not significantly associated with CCT (p=0.643 and p=0.632).
CCT and corneal haze are important features that should be taken into consideration when assessing and managing pediatric anterior segment disorders, congenital glaucoma, and subsequently resulting amblyopia. With the growing evidence that prematurity is a risk factor for congenital glaucoma and angle abnormality, it is crucial to have a good understanding of CCT and its change over time in premature infants and associated systemic features. This study by Islam's group is the first study to investigate CCT and associated systemic features in a racially diverse population, as opposed to racially homogenous populations in previous studies. Hence, given its higher external validity in comparison to the previous papers on CCT, this study's findings may have higher applicability and clinical utility, especially in Canada, one of the most ethnically diverse nations in the world. Furthermore, this study is the first to study the relationship between CCT and steroid/ oxygen use exclusively in pre-term infants, adding more originality to it. Many pre-term infants may often require oxygen/ steroid treatment as they are at high risk for airway diseases such as respiratory distress syndrome and bronchopulmonary dysplasia. This study's novel findings provide reassurance that neither oxygen nor steroid use has any effect on CCT. To conclude, Islam's group presents a valuable original study that is an asset to the current literature that unfortunately does not have much information on CCT in preterm infants. Larger studies in the future can hopefully help reinforce and expand the findings discovered by Islam's group.