The Significance of External Limiting Membrane Status for Visual Acuity in Age-related Macular Degeneration

Purpose: To evaluate status of the external limiting membrane (ELM) as a contributor of visual acuity (VA) in age-related macular degeneration (AMD).

Design: Hospital-based, cross-sectional study.

Methods: We retrospectively reviewed spectral-domain optical coherence tomography images of 158 patients with AMD who had undergone photodynamic therapy and classified them based on the status of the ELM: absent, discontinuous, or complete. We simultaneously assessed foveal thickness, presence or absence of subretinal fluid/mass, presence or absence of subretinal pigment epithelium fluid/mass, status of the inner segment/outer segment (IS/OS) junction, and status of the intermediate line between the IS/OS junction and retinal pigment epithelium. Correlation coefficients between each parameter and VA were analyzed.

Results: There was a strong correlation between ELM status and VA (r = -0.75, P < .001), and that was higher than that of the IS/OS (r = -0.69, P < .001). Multivariate analysis showed that ELM status is the most important factor for VA. Other parameters that correlated with VA included age, status of the intermediate line, and presence of subretinal or subretinal pigment epithelium fibrosis. Foveal thickness showed V-shaped correlation, with the dividing line around 200 mum.

Conclusion: ELM status may be more useful than is IS/OS status in evaluation of retinal morphology and function in patients with AMD.