Evaluation of Corneal Biomechanical Properties Following Penetrating Keratoplasty Using the Ocular Response Analyzer

PURPOSE: To evaluate corneal biomechanical properties in eyes that had previously undergone penetrating keratoplasty (PK) using the ocular response analyzer (ORA). METHODS: 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. RESULTS: 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 µm and 556.24±42.84 µm in post-PK and control eyes, respectively (p=0.068). CONCLUSIONS: 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.