Biomechanical properties of keratoconus suspect eyes.

PURPOSE: Measuring corneal biomechanical properties may help detect keratoconus suspect corneas and eliminate the risk of ectasia after LASIK.

METHODS

Data of 504 eyes separated into three groups were retrospectively reviewed: normal (n = 252), keratoconus suspect (n = 80), and keratoconus (n = 172). Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured with an ocular biomechanics analyzer.

RESULTS

Mean corneal hysteresis was 10.6 +/- 1.4 (SD) mm Hg in the normal group, compared with 10.0 +/- 1.6 mm Hg in the keratoconus suspect group and 8.1 +/- 1.4 mm Hg in the keratoconus group. The mean CRF was 10.6 +/- 1.6 mm Hg in the normal group compared with 9.7 +/- 1.7 in the keratoconus suspect group and 7.1 +/- 1.6 mm Hg in the keratoconus group. Mean CH and CRF were significantly different between the three groups (P < 0.001).

CONCLUSIONS

CH and CRF alone cannot be used to identify keratoconus suspect corneas. Analyzing signal curves obtained with the biomechanics analyzer may provide additional valuable information for selecting qualified patients for refractive surgery.