Graft Biomechanics Following Three Corneal Transplantation Techniques

PURPOSE: To compare corneal biomechanical properties following three different transplantation techniques, including Descemet stripping automated endothelial keratoplasty (DSAEK), deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in comparison to normal eyes. METHODS: This cross-sectional comparative study included 118 eyes: 17 eyes of 17 patients received DSAEK, 23 eyes of 21 patients underwent DALK using Anwar's big bubble technique, and 45 eyes of 36 patients had PK; 33 right eyes of 33 normal subjects served as the control group. Using the ocular response analyzer (ORA, Reichert Ophthalmic Instruments, Buffalo, New York, USA), corneal hysteresis (CH) and corneal resistance factor (CRF) were measured and compared among the study groups at least 3 months after all sutures were removed. RESULTS: Mean patient age was 26.9 ± 5.0 years in the control group, 28.8 ± 4.2 in the PK group, 27.2 ± 6.5 in the DALK group, and 62.5 ± 16.8 in the DSAEK group (P < 0.001). Central corneal thickness (CCT) was 539.0 ± 24.8, 567.5 ± 38.8, 547.0 ± 42.6 and 631.1 ± 84.8 μm, respectively (P < 0.001). CH and CRF were significantly lower in the DSAEK group (7.79 ± 2.0 and 7.88 ± 1.74 mmHg, respectively) as compared to the PK (10.23 ± 2.07 and 10.13 ± 2.22 mmHg, respectively) and DALK (9.64 ± 2.07 and 9.36 ± 2.09 mmHg, respectively) groups. The two latter groups demonstrated biomechanical parameters comparable to normal subjects (9.84 ± 1.59 and 9.89 ± 1.73 mmHg, respectively). CONCLUSION: Graft biomechanical parameters after DSAEK are lower than those following PK and DALK. After PK and DALK in keratoconic eyes, these metrics are increased to normal values. These differences may have implications for interpreting intraocular pressure or planning graft refractive surgery after keratoplasty.