Surface-Specific Internal Limiting Membrane Biomechanics in Epiretinal Membrane Severity and Visual Outcomes

Purpose: To determine whether surface-specific biophysical properties of the internal limiting membrane (ILM), measured by atomic force microscopy (AFM), are associated with optical coherence tomography (OCT)–based epiretinal membrane (ERM) stage and six-month visual outcomes. Methods: In this prospective study, ILM specimens from vitrectomy for idiopathic ERM (stages 2–4) were examined by AFM for thickness, roughness, stiffness, and adhesion on the vitreal or retinal surface. AFM parameters were related to preoperative OCT parameters, best-corrected visual acuity, surgical grade of ILM adherence, and six-month outcomes. Multivariable regression assessed correlates of visual change and final acuity. Results: We analyzed 147 eyes (80 retinal-side, 67 vitreal-side). Retinal-side roughness and stiffness exceeded vitreal-side values (both P < 0.001). Retinal-side roughness and adhesion (P < 0.001 and P = 0.008, respectively) and, less strongly, vitreal-side stiffness (P = 0.035) increased with ERM stage, whereas vitreal-side adhesion did not. Thickness did not differ by surface or stage (all P ≥ 0.116). Retinal-side roughness and adhesion correlated with preoperative severity and postoperative outcomes, whereas vitreal-side stiffness correlated mainly with severity and vitreal-side adhesion with surgical adherence. Greater retinal-side adhesion and vitreal-side stiffness were associated with smaller visual gains and worse final acuity in multivariable models (all P < 0.05). Conclusions: ILM biophysical properties showed surface-specific associations with OCT-based ERM severity and six-month visual outcomes. Retinal-side adhesion and vitreal-side stiffness remained associated with final acuity after adjustment for baseline acuity. These findings suggest that ILM surface mechanics may reflect ERM-related retinal deformation relevant to postoperative visual recovery.