Researchers in Germany report that extreme prematurity itself—not necessarily the occurrence of retinopathy of prematurity (ROP)—is associated with increased higher-order aberrations of the cornea in former preterm infants.1 These findings were unexpected, said lead author Achim Fieß, MD, at the University Medical Center in Mainz.
Study design. The prospective cross-sectional study compared the corneal shape of 226 former preterm infants, of a gestational age (GA) of ≤ 32 weeks, with 259 randomly selected children who had been born at full term (GA ≥ 37 weeks).
The researchers evaluated differences in various corneal aberrations in relation to gestational age and ROP occurrence in these children. The various aberrations included astigmatism, coma, spherical aberration, and root-mean square of higher-order aberrations.
The subjects ranged in age from 4 to 10 years, an age group selected because little is known about the association between prematurity and altered corneal shape in early childhood, Dr. Fieß said. “We decided to investigate this age group to provide new insights for corneal aberration development in this decisive time frame of vision development.”
Dr. Fieß added that the study was possible only because of modalities, such as Scheimpflug imaging, which allows no-contact examination of the anterior segment. This is ideal for observing children in detail.
Findings. In general, total corneal aberrations, both lower- and higher-order, increased as gestational age declined, with effects observed mainly on the anterior surface of the cornea.
Yet because infants on the older end of the preterm spectrum (GA of 29-32 weeks) had corneal aberrations comparable to those children born at full term, the researchers refined the age parameters into moderate and extreme prematurity. It was extreme prematurity that was associated with increased higher-order and lower-order aberrations of the total cornea.
Clinical implications. While corneal aberrations may be one of several factors contributing to increased refractive error and low visual function, particularly in former extreme preterm infants, the visual effects of aberrations are expected to be small compared to myo pia or astigmatism, Dr. Fieß said. “Our finding, therefore, is less important for guiding treatment than it is for suggesting a further reason for low visual acuity and refractive error in former preterm children.”
Does the effect persist? Dr. Fieß is currently investigating the effect of low birth weight on ocular morphology in an adult cohort. This may determine whether corneal aberrations persist into adulthood in former preterm infants.
In the meantime, he said, “Our study highlights that, in particular, gestational age less than 29 weeks affects corneal shape. Extreme early prematurity is one decisive factor affecting corneal aberrations.”
1 Fieß A et al. Invest Ophthalmol Vis Sci. 2017;58(14):6374-6378.
Relevant financial disclosures—Dr. Fieß: None.
For full disclosures and the disclosure key, see below.
Full Financial Disclosures
Dr. Adrean Allergan: C,S; Genentech: C,S; Ohr Pharmaceuticals: C,S; Ophthotech: C,S; Regeneron: C,S; SciFluor Life Sciences: C,S.
Dr. Fieß None.
Dr. Medeiros Alcon: C; Allergan: C; Bausch + Lomb: S; Carl Zeiss: C,S; Heidelberg Engineering: C,S; Merck: S; NIH: S; Novartis: C; Sensimed: S; Topcon: S; Reichert: C,S.
Dr. Whalen None.
||Consultant fee, paid advisory boards, or fees for attending a meeting.
||Employed by a commercial company.
||Lecture fees or honoraria, travel fees or reimbursements when speaking at the invitation of a commercial company.
||Equity ownership/stock options in publicly or privately traded firms, excluding mutual funds.
||Patents and/or royalties for intellectual property.
||Grant support or other financial support to the investigator from all sources, including research support from government agencies (e.g., NIH), foundations, device manufacturers, and/or pharmaceutical companies.
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