Genetics may factor into keratoconus and high corneal curvature, a new study in Eye & Contact Lens reports.

In an effort to investigate familial aggregation of anterior and posterior corneal curvature, corneal astigmatism and some corneal topometric indices, Iranian researchers enrolled 1,383 individuals representing 382 families in this study. Analysis was based on topography Pentacam (Oculus) measures from at least two family members (father or mother and a child). All subjects underwent refraction, uncorrected and corrected visual acuity measurement, slit lamp biomicroscopy and topography. Researchers used heritability estimation to calculate familial aggregation.

“The results of our study showed a fairly high corneal curvature heritability,” researchers said. The heritability rate in the anterior surface was 58.61% in K2 and 55.82% in K1, the investigators noted in their paper.

Researchers found the heritability of posterior corneal curvature was slightly higher. The heritability of K2 in the posterior surface was 63.42% and 59.67% in K1. The quantitative topographic corneal indices showed the index of surface variance, central keratoconus index and index of vertical asymmetry had the highest levels of heritability (81.2%, 75.21% and 66.46%, respectively). However, keratometric power deviation and index of height asymmetry had the lowest heritability levels (7.48% and 18.31%, respectively).

These findings “confirm a high correlation between these phenotypes and genetic factors and warrant further investigation of the genetic mechanisms in keratoconus,” researchers said. 

Heydarian S, Hashemi H, Yekta A, et al. Heritability of corneal curvature and Pentacam topometric indices: a population-based study. Eye Contact Lens. February 28, 2019. [Epub ahead of print].