Internal limiting membrane: ultrastructural relationships, with clinical implications for macular hole healing

Abstract

Background: Recent data on macular hole formation have changed our understanding of the mechanisms involved. However, the mechanisms of macular hole closure, despite the introduction of internal limiting membrane (ILM) removal, are not fully understood. We reviewed the charts of patients who underwent surgery for macular hole with and without intentional removal of ILM and reviewed the basic science literature on the components and relationships of the ILM-glial cell interface to help interpret our surgical data.Methods: We reviewed the records of 205 eyes with a clinical diagnosis of macular hole at a university centre in Montreal between 1998 and 2002. Of these, 117 eyes of 108 patients were included. Vitrectomy with intentional ILM removal was done under indocyanine green (ICG) staining. Macular hole stage and rates of hole closure, failure and reopening were recorded, comparing the eyes with intentional ILM peeling versus no ILM peeling. Anatomic success was defined as a flat/closed configuration. A basic science literature review was done through the PubMed search engine with the key words “internal limiting membrane”, “internal limiting lamina”, “macular hole”, “retinal glial cells” and “retinal Muller cells”.Results: Eighty-four eyes had ICG-guided ILM removal (26 stage 2 macular holes, 45 stage 3 holes and 13 stage 4 holes), and 33 eyes had no ILM removal (10 stage 2 holes and 23 stage 3 holes). Of the 117 eyes 110 (94.0%) were successfully closed. Four (3.6%) of the closed holes reopened (none had ILM peeling), and 7 (6.0%) of the 117 eyes had primary failure. Ten of the 11 eyes that had primary failure or hole reopening were reoperated, and 8 were successfully closed after the second procedure. One patient refused reoperation. Including second procedures, the final anatomic closure rate was 97.4% (114/117).Interpretation: Intentional ILM peeling is not mandatory for all macular holes to close but does play a role in preventing reopening. Removal of ILM increases the rate of flat/closed hole configuration on reoperation without the need for biologic adjuvants. Review of the basic science evidence helped clarify the possible role of ILM removal.