Researchers have identified over 200 genes that influence the viscoelastic properties of the cornea.1 The genes—all but eight of which are novel—are significantly associated with two corneal biomechanical properties: corneal hysteresis (CH) and corneal resistance factor (CRF).
The discovery was made in a genome-wide association study (GWAS) that was designed to explore the genetic architecture of CH and CRF and to clarify their genetic correlation with eye and systemic disease. “Understanding the underlying genetics of these traits allows us to understand the mechanisms that might be involved in the variation of viscoelastic properties of the cornea,” said Christopher J. Hammond, FRCOphth, MD, at King’s College London in the United Kingdom.
Study findings. The study involved over 100,000 participants drawn from UK Biobank, a population-based cohort between the ages of 40 and 69. An analysis of their CH and CRF measures found a significant association for expression of 86 genes with CH and 107 with CRF. Most were expressed in corneal tissue.
The study also identified 21 genetic loci implicated in keratoconus, 22 loci associated with Fuchs dystrophy, and many novel associations, including a component in collagen-related pathways that influences corneal biomechanical properties.
The GWAS also identified, for the first time, traits such as lung function and height that have shared genetic variants in the cornea. This finding possibly relates to elasticity of tissues, Dr. Hammond said.
A weak IOP correlation. It has been suggested that CH and CRF may be predictors of glaucoma, independent of elevated IOP. However, in this study, CH was negatively correlated with applanation pressures. CRF was positively correlated with applanation pressures, but only to a small degree. Dr. Hammond said the analyses show that IOP alters CH and CRF, rather than the other way around.
Looking ahead. “This study shows the complexity of the eye and its traits and [points out] that different genetic traits are related to each other in the eye,” Dr. Hammond said. “Knowledge gained might improve future treatments for corneal diseases that are associated with abnormal corneal elasticity, such as keratoconus.”
1 Simcoe MJ et al. Hum Mol Genet. Published online July 27, 2020.
Relevant financial disclosures—Dr. Hammond: None.
For full disclosures and the disclosure key, see below.
Full Financial Disclosures
Dr. Calkins None.
Dr. Hammond None.
Dr. Kempen CBM: S; Gilead: C; NEI: S; Sight for Souls: S. In addition, the MUST Trial received a donation of fluocinolone acetonide intraocular implants from Bausch + Lomb for patients who would be unable to enroll in the trial without a donated implant.
Dr. Lim Heidelberg Engineering: L; National Healthcare Group Eye Institute, Tan Tock Seng Hospital: S; Novartis: C.
||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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