Corneal biomechanical properties in normal, regular astigmatic, and keratoconic eyes

Corneal hysteresis (CH) is a parameter which measures the viscoelastic behaviour of the cornea, indicating its biomechanical integrity1. Some clinical conditions such as keratoconus, Fuchs corneal dystrophy, high myopia, glaucoma and corneal refractive surgery, may induce changes in corneal biomechanical properties, leading to a decrease in CH2-6. Astigmatism, a refractive error related to corneal asphericity, can be congenital or acquired. The most severe astigmatism is generally acquired as a result of surgery, trauma, or primary corneal ectasia such as keratoconus. Keratoconus (KC) is an ectasic corneal disorder characterized by a progressive corneal thinning which results in corneal protrusion, irregular astigmatism and decreased vision. Previous studies evaluated