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

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.

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.

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).

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.