Biomechanical evaluation of cornea in topographically normal relatives of patients with keratoconus

To compare the biomechanical properties of the cornea between topographically normal relatives of patients with keratoconus and age-matched controls.

Thirty healthy individuals (control group) and 30 topographically normal relatives of patients with keratoconus (study group) were enrolled in this prospective, cross-sectional comparative study. Topographical measurements including pachymetric values, keratometry values, irregularity, and inferior-superior dioptric asymmetry difference values in the right eye of each participant were obtained using Orbscan II (Bausch & Lomb Laboratories, Inc, Rochester, NY). Corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated intraocular pressure, and Goldmann-related intraocular pressure were also measured using the Reichert Ocular Response Analyzer (ORA).

Topographic parameters were not significantly different between both groups (P > 0.05). Mean CH was 9.9 ± 1.6 mm Hg in the study group and 11.3 ± 1.0 mm Hg in the control group (P = 0.001); mean CRF was 9.8 ± 1.6 mm Hg and 11.2 ± 2.1 mm Hg in the study and control groups, respectively (P = 0.013). Mean Goldmann-related intraocular pressure was 15.0 ± 4.3 mm Hg in the study group and 15.8 ± 6.7 mm Hg in the control group (P = 0.603); mean corneal compensated intraocular pressure was 16.2 ± 4.7 mm Hg in the study group and 15.4 ± 5.8 mm Hg in the control group (P = 0.595).

The CH and CRF values were significantly lower in the relatives of patients with keratoconus than in the controls. Future studies including monitoring of these participants with topographical and biomechanical measurements may indicate the role of this study in detection of early corneal changes in relatives of patients with keratoconus.