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Biomechanical characteristics different in keratoconus, normal eyes
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The majority of biomechanical characteristics in keratoconus eyes differ significantly with those in normal eyes, according to a study.
The study included 70 eyes of 37 keratoconus patients and 70 eyes of 37 age- and sex-matched controls. Keratoconus severity was determined by anterior corneal curvatures, difference in astigmatism in each meridian, anterior best-fit sphere and posterior best-fit sphere.
The Ocular Response Analyzer (Reichert) measured the air pressure and corneal deformation relationship between the keratoconus and control groups. Four repeat air pressure profiles were averaged, with 42 separate parameters examined.
Overall, the biomechanics in keratoconus eyes were statistically significantly different than those found in normal eyes (P < .001). Study results showed that the cornea was thinner (P < .001), the speed of corneal concave deformation past applanation was quicker (P = .01) and the tear film index was lower (P = .01) with increasing severity of keratoconus.
“The corneal biomechanical changes with keratoconus, as assessed by the parameters of [central corneal thickness], [corneal hysteresis] and [corneal resistance factor], are more complex than clinical signs, and front corneal surface changes indicate that other corneal biomechanical characteristics should be considered,” the study authors said.
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