Study links IOP with wavefront-measured aberrations in myopic eyes

IOP was associated with both symmetrical wavefront-measured aberrations and asymmetrical higher-order aberrations in patients with myopia, a study by researchers in China found. Central corneal thickness, however, showed only weak associations with the aberrations, the study authors noted.

Jia Qu, MD, and colleagues at Wenzhou Medical College investigated the association between IOP, central corneal thickness (CCT) or both and wavefront aberrations in the anterior cornea and entire eye of 70 patients with myopia. Wavefront aberrations in the anterior corneal surface were tested with a Humphrey corneal topographer, and wavefront aberrations in the whole eye were tested with the Complete Ophthalmic Analysis System (Carl Zeiss Meditec), according to the study.

Four corneal Zernike aberrations significantly correlated with IOP — defocus, Z4; spherical aberration, Z12; secondary astigmatism, Z13; and y-axis coma, Z7.

In the anterior corneal surface, defocus was always positive and increased with IOP. Spherical aberration was usually positive and also increased with IOP. Secondary astigmatism decreased with IOP, while corneal y-axis coma increased with IOP, according to the study.

In the entire eye, three Zernike aberrations significantly correlated with IOP - spherical aberration, Z12; trefoil, Z6; and secondary astigmatism, Z13. Whole-eye spherical aberration was usually positive and increased with IOP, while trefoil and secondary astigmatism in the whole eye decreased with IOP, the authors reported.

Only a single Zernike aberration — Z11 — significantly correlated with CCT. This was secondary astigmatism, which decreased with CCT, they noted.

The study is published in the August issue of Journal of Cataract & Refractive Surgery.