Finite element analysis of cornea deformation and curvature change during the keratoplasty suturing process

Keratoplasty, which is cornea transplant surgery, is one of the treatment methods for patients with turbidity or keratitis. Recently, keratoplasty using a surgical robot was studied to increase precision. In this study, the effect of surgical factors on the deformation and curvature of the cornea were analyzed in order to improve the accuracy of keratoplasty and derive the optimal surgical factors using finite element method (FEM). Suturing tension and depth were selected as surgical factors. An FEM model, a constitutive equation, and boundary conditions were determined using experiments and reference data. Suturing tension significantly impacted deformation and curvature change, and suturing depth affected the position of the thread-cornea contact point. Both factors have a significant impact on a focal point in the retina and the patient's visual acuity after keratoplasty.

Factors Affecting Acute Pain Management for Ureter Stone Patients in the Emergency Department

PURPOSE: The most important step for patients who come to the emergency department with ureter stones is acute pain management. There have been insufficient studies on what factors affect acute pain management for ureteral colic the most. In this study, patients with ureteral colic were divided into two groups: one group, in which the pain was first managed with an analgesic, and another group with unmanaged pain, to find factors that most affect additive analgesics administration for ureter stones. METHODS: There were 121 patients, eventually confirmed for the presence of ureter stones through a computed tomography CT scan, included in this study. When ureter stones were suspected after the initial patient evaluation, initial pain was assessed through numerical rating scale (NRS) and the first analgesic was administered once. Pain was reassessed through NRS after 30 minutes. At that time, if the pain was managed, the patient was assigned to Group 1. If the pain persisted, another analgesic was administered for the second and third time, and the patient was assigned to Group 2. Finally, ureter stones were identified through CT scan. RESULTS: There were 58 patients (47.9%) in Group 1 and 63 patients (52.1%) in Group 2. There were no statistically significant differences in average age, serum creatinine, size of ureter stone, and severity of hematuria between the two groups. The differences in NRS measured initially and after 30 minutes were statistically significant (7.6+/-1.4 vs. 8.6+/-1.2, p<0.001; 1.4+/-1.3 vs. 6.6+/-1.9, p<0.001, respectively). The presence of hydronephrosis and perirenal edema were also statistically significant (p<0.001, p=0.007). The affecting factor for the administration of additive analgesics was hydronephrosis (odds ratio 7.213, p<0.001). CONCLUSION: Hydronephrosis is an important factor in the treatment of patients with additive analgesics. It can also be used as a predictive index to assess the severity of pain in patients with ureter stones.