Corneal Biomechanics Before and After Descemet Membrane Endothelial Keratoplasty in Patients with Fuchs Endothelial Corneal Dystrophy

Usanee Reinprayoon,1– 3 Sasi Yaisawang,1 Nipan Israsena,3,4 Lita Uthaithammarat,5 Ngamjit Kasetsuwan1,2 1Cornea and Refractive Surgery Unit, Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; 2Center of Excellence for Cornea and Stem Cell Transplantation, Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; 3Clinical Excellence Center for Stem Cells and Cell Therapy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; 4Department of Pharmacology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; 5Department of Ophthalmology, Banphaeo General Hospital, Samutsakhon, ThailandCorrespondence: Usanee Reinprayoon, Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, 1873, Rama 4 Road, Pathumwan Sub-District, Pathumwan District, Bangkok, 10330, Thailand, Tel +66816186025, Email [email protected]: Descemet Membrane Endothelial Keratoplasty (DMEK) is a surgical intervention for restoring endothelial function in Fuchs endothelial corneal dystrophy (FECD). However, changes in corneal biomechanical properties assessed using dynamic Scheimpflug analyzer (DSA) remain limited. This study aimed to assess alterations in corneal biomechanical parameters before and after surgery in patients with FECD using DSA.Patients and Methods: This prospective study included 24 FECD patients. Demographic data, visual acuity, central corneal thickness (CCT), endothelial cell count, intraocular pressure (IOP), stress strain index (SSI) and others DSA parameters were evaluated. Measurements were obtained preoperatively and at 1, 3, and 6 months after surgery. Repeated measures analysis of variance and pairwise correlations were used to assess differences and associations.Results: Significant postoperative alterations were observed in multiple corneal biomechanical parameters. CCT, ARTh, A1 length, A1 DefA and SPA showed significant reductions over time. Conversely, the DefA max, maximum inverse radius, DA ratio, integrated radius and CBI significantly increased during follow-up. While, SSI remained stable at all time points. These findings demonstrate a biomechanical transformation following DMEK from 1 to 6 months postoperatively, reflecting the transition from a swollen, thickened cornea to a thinner, clearer cornea in the postoperative state.Conclusion: DMEK resulted in reduced corneal thickness and significant changes in several corneal biomechanical parameters. However, the stability of SSI, which is independent of CCT and bIOP, suggests that intrinsic corneal stiffness remains unchanged despite postoperative remodeling. The observed biomechanical alterations may provide useful markers for monitoring corneal recovery following DMEK.Plain Language Summary: Fuchs Endothelial Corneal Dystrophy (FECD) is a common condition that affects the back layer of the cornea. In FECD, the cells that keep the cornea healthy gradually die, causing swelling, blurred vision, and glare. Descemet Membrane Endothelial Keratoplasty (DMEK) can replace the damaged cells and restore vision. However, DMEK’s effect on cornea strength and how it responds to pressure remains unclear.In this study, we followed 24 patients with FECD who underwent DMEK surgery. We measured how their corneas responded to small air pulses using a special imaging tool called a Dynamic Scheimpflug Analyzer. We also measured corneal thickness, eye pressure, and vision before surgery and 1, 3, and 6 months afterward.We found that DMEK improved vision and reduced corneal swelling in all patients. Many of the cornea’s mechanical properties changed after surgery, mostly because the cornea became thinner and less swollen. Importantly, the stress–strain index, which reflects the cornea’s true stiffness, did not change. This means that DMEK restores corneal shape and function without altering the tissue’s natural strength.These results show that DMEK effectively improves vision and corneal health. Measuring corneal properties after surgery can help doctors monitor recovery and understand how the cornea adapts. This research also highlights which measurements reflect real tissue changes and which are influenced by swelling, guiding future studies and patient care.Keywords: corneal stiffness, corneal remodeling, Fuchs endothelial corneal dystrophy, Corvis ST, corneal edema, dynamic Scheimpflug analysis, descemet membrane endothelial keratoplasty, stress–strain index