Abstract:

Objective To describe the change of the corneal biomechanical parameter and intraocular pressure(IOP) for kerotoconus eyes before and after the collagen crosslinking procedure (CXL). Design Cohort study. Participants 23 cases of keratoconus (41 eyes).  Method All patients undergo refractive examination, central corneal thickness(CCT), non-contact tonometer (NCT) , and ocular response analyzer (ORA) before CXL surgery, and 1 week, 1, 3, 6, and 12 months after CXL surgery. Corneal hysteresis (CH), corneal resistance factor (CRF), simulated Goldmann intraocular pressure (IOPg) and corneal compensated intraocular pressure (IOPcc) were measured with ORA. The changes of parameters before and after CXL surgery were compared and the correlation between the changes of corneal biomechanical parameters and IOP was analyzed. Main Outcome Measures Visual acuity, optometry, CCT, IOPcc, CH, CRF. Result The preoperative CH of the keratoconus of 41 eyes was 8.044±1.264, and it decreased to 7.817±1.561 1 year after operation, which was statistically different from that before operation (t=2.48, P=0.01). The preoperative CRF was 6.846±1.353, and the postoperative 1 year was 6.687±1.233, which was not statistically different from the preoperative (t=-0.55, P=0.58). At 1 year after CXL surgery, NCT IOP was positively correlated with IOPg (r=0.724, P<0.001), IOPcc (r=0.613, P<0.001), and CRF (r=0.513, P<0.001). Conclusion At 1 year after CXL surgery, the CH value decreased compared with preoperative, and the CRF value did not change compared with preoperative. There is a medium-intensity positive correlation between NCT intraocular pressure and IOPg, IOPcc and CRF values. The change in NCT intraocular pressure value, to some extent, can reflect the change of CRF value. (Ophthalmol CHN, 2019, 28: 297-301)

Key words: keratoconus, collagen cross-linking, corneal biomechanics