Finite element analysis explores ablation depth and optical zone as key determinants of intraocular pressure reduction after refractive surgery.

BACKGROUND

with the increasing prevalence of refractive surgery, its impact on intraocular pressure (IOP) measurement has gained significant attention. This study aimed to elucidate the mechanism by which femtosecond laser-assistedin situkeratomileusis (FS-LASIK)-induced geometric alterations of the cornea affect IOP measurements obtained with the Goldmann applanation tonometer (GAT).

METHODS

IOP was measured with the GAT in patients undergoing FS-LASIK preoperatively and at 3 and 6 months postoperatively. A corneal finite element (FE) model, including aqueous humor for both pre- and post-operative states, was created to simulate the surgical volume required for correcting myopia of -2, -4, and -6 diopters (D). IOP values were calculated based on the principle of the GAT, and FE simulation results were compared with clinical IOP data measured using the GAT to validate the model.

RESULTS

Clinical data from GAT measurements demonstrated a consistent decrease in IOP following surgery. FE results indicated that the postoperative IOP, ranging from 8.26 mmHg to 13.04 mmHg, decreased by 23%-51% compared to the preoperative IOP of 17.04 mmHg. Deeper ablation depths and larger optical zone diameters were associated with lower postoperative IOP.

CONCLUSION

The FE analysis demonstrated a decreasing trend in postoperative IOP with increasing ablation depth and optical zone diameter. These findings provide valuable insights for guiding postoperative IOP monitoring, optimizing surgical parameters, and understanding postoperative corneal biomechanical behavior.