Graft Biomechanical Properties Following Three Corneal Transplantation Techniques

To investigate the biomechanical features of transplanted corneas after penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), and Descemet stripping automated endothelial keratoplasty (DSAEK) and compare these measurements with those of a normal group. Forty-five eyes of 36 patients underwent PK, 23 eyes of 21 patients received DALK using Anwar’s big bubble technique, and 17 eyes of 17 patients had DSAEK. Thirty-three right eyes of 33 normal subjects served as controls. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured at least 3 months after complete suture removal using the Ocular Response Analyzer. These parameters were compared between the study groups using the one-way ANOVA test. The mean age was 26.9±5.0 years in the control group, 28.8±4.2 years in the PK group, 27.2±6.5 years in the DALK group, and 62.5±1.8 in the DSAEK group (P<0.001). Central corneal thickness was 539.0±24.8, 567.5±38.8, 547.0±42.6, and 631.1±84.8 m, 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) than in 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 results comparable to the normal subjects (9.84±1.59 and 9.89±1.73 mmHg, respectively). The graft biomechanics after DSAEK are lower than those after PK and DALK. Both PK and DALK can increase these metrics in keratoconic eyes to normal values. These differences should be considered when interpreting intraocular pressure or planning grafts refractive surgery after keratoplasty.