Resumen de Corneal biomechanical properties in normal, regular astigmatic, and keratoconic eyes
María Ángeles del Buey Sayas, José Angel Cristóbal Bescós, Francisco Javier Ascaso Puyuelo, L. Lavilla-García, Elena Lanchares
PURPOSE: To compare the biomechanical properties of normal, regular astigmatic, and keratoconic corneas.
METHODS: Corneal hysteresis (CH), corneal resistance factor (CRF), central corneal thickness (CCT), Goldmann correlated intraocular pressure (IOPg) and corneal compensated IOP (IOPcc) were measured with the ocular response analyzer (ORA) in 93 normal, 56 astigmatic, and 39 keratoconic eyes.
RESULTS: Mean astigmatism values were 0.50, 3.76, and 5.29 diopters in control, astigmatic and keratoconic group, respectively. Mean CH was significantly lower in keratoconic (7.9±1.4 mmHg) than in control (10.7±1.3 mmHg) and astigmatic (10.5±1.8 mmHg) eyes. Mean CRF was 7.1±1.7 mmHg in keratoconic group, 10.5±1.3 mmHg in control group, and 10.5±2.1 mmHg in astigmatic group. Both differences were statistically significant (p=0.0001). CCT was lower in keratoconus (463.3±42.7 µm) than in control (554.0±28.5 µm; p=0.0001), and astigmatic eyes (556.2±39.9 µm; p=0.0001). IOPg in keratoconic eyes (11.2±3.5 mmHg) was lower than in the control (14.8±2.4 mmHg;
p=0.0001) and astigmatic group (15.5±3.8 mmHg; p=0.0001). No significant differences of IOPcc were present among the three groups (p=0.239). Mean CH-CRF was higher in keratoconic (0.9±1.0 mmHg) than in normal (0.2±0.7 mmHg; p=0.011) and astigmatic eyes (0.0±1.1 mmHg; p=0.0001). CONCLUSIONS. Keratoconic eyes, unlike astigmatic and normal eyes, have different corneal biomechanical properties. ORA may be a useful technique for the differential diagnosis between regular astigmatism and astigmatism caused by keratoconus.
