Biomechanical Property of Keratoconus Measured by ORA

ABSTRACT

PURPOSE: To compare the biomechanical properties of keratoconus, keratoconus suspect, and normal subjects measured by ocular response analyzer. METHODS: A total of 72 patients were divided into 3 groups keratoconus, suspected keratoconus, and normal control subjects. The 3 age-matched groups were evaluated according to age, sex, and visual acuity. Slit lamp examinations, Pentacam, and ocular response analyzer (ORA) examinations were performed. Mean corneal refractive power, central corneal thickness, corneal hysteresis (CH), and corneal resistance factor (CRF) were evaluated and analyzed. RESULTS: Twenty-four eyes were included in each group. The mean age was 23.8 years in keratoconus, 26.0 years in suspected keratoconus and 26.1 years in normal subject groups. Mean corneal refractive power was significantly higher in keratoconus (p < 0.001) and suspected keratoconus (p = 0.001) groups than in the normal subject group. Mean central corneal thickness showed significant differences among the 3 groups (p < 0.05). CH was significantly lower in keratoconus than suspected keratoconus (p = 0.025) and normal subject groups (p = 0.005), but showed no significant difference between suspected keratoconus and normal subject groups. CRF showed significant differences among all 3 groups (p < 0.05). CH and CRF had negative correlations with mean corneal refractive power and positive correlations with central corneal thickness. CONCLUSIONS: CH and CRF measured by ORA were significantly different between keratoconus and normal subject groups and had significant correlations with mean corneal refractive power and central corneal thickness. CRF may be a useful method to differentiate between suspected keratoconus and normal cornea patients.