Evaluation of corneal biomechanical properties following penetrating keratoplasty using the ocular response analyzer

To evaluate corneal biomechanical properties in eyes that had previously undergone penetrating keratoplasty (PK) using the ocular response analyzer (ORA). We recruited 26 patients who had received unilateral PK. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and cornea-compensated intraocular pressure (IOPcc) were measured with the ORA and were compared to the measurements from the contralateral eyes that did not undergo PK. The CH was 8.95+/-2.59 mmHg in eyes that underwent PK and 9.78+/-1.45 mmHg in the contralateral eyes that did not undergo PK (p=0.077). The CRF was 10.26+/-2.64 mmHg in post-PK eyes and 9.75+/-1.45 mmHg in the contralateral eyes (p=0.509), and the CH-CRF was significantly smaller in post-PK eyes (-1.31+/-2.32 mmHg in post-PK eyes vs. 0.03+/-0.88 mmHg in fellow eyes, p=0.016). The IOPg and IOPcc were significantly higher in the PK group than they were in the control group. The IOPcc's were 20.81+/-7.81 mmHg and 16.27+/-2.49 mmHg in post-PK and control eyes, respectively (p=0.011); and the IOPg's were 19.22+/-7.34 mmHg and 15.07+/-3.03 mmHg in post-PK and control eyes, respectively (p=0.019). The IOPcc-g's were 1.59+/-2.81 mmHg and 1.21+/-1.30 mmHg in post-PK and control eyes, respectively (p=0.412), and the central corneal thickness (CCT)'s were 489.11+/-90.60 microm and 556.24+/-42.84 microm in post-PK and control eyes, respectively (p=0.068). Following PK, CH tended to decrease while CRF tended to increase, significantly decreasing CH-CRF. A significantly higher intraocular pressure and a thinner CCT following PK may have contributed to the observed changes in these corneal biomechanical parameters.