Surgical characteristics of the retinal inner limiting membrane

In a recent issue of the BJO Steven et al describe secondary retinal holes after removal of the inner limiting membrane (ILM).¹ We consider this a key retinal publication and therefore wish to strengthen the importance of the authors' findings for modern surgery of the vitreoretinal interface.

Interestingly, the paper included only patients with macular puckers and cystoid macular oedema, but not macular holes. In cases of macular holes only a small sized central part of the ILM will usually be peeled. In contrast, macular puckers and cystoid oedemas will typically affect a larger region of the posterior pole. Thus a more extensive fraction of the ILM will be stripped if surgery is performed in such cases.

More than 30 years ago Foos² described two anatomical features of the ILM that might explain why current peeling of the peripheral ILM may be unsafe. Firstly, the ILM is thickest at the posterior pole and will become continuously thinner in the periphery. In the initiation of the ILM removal this may increase the risk for direct retinal trauma. Secondly, the Müller glia are more strongly attached to the ILM away from the macula. This may lead to indirect surgical trauma of the non‐neuronal parts of the retina during the peeling process.

In conclusion, the more eccentric from the macula, the thinner and the more adherent to the retina is the ILM. As described by Steven et al, removal of these peripheral ILM fractions may lead to retinal hole formation.¹ Direct and/or indirect surgical trauma may be responsible for such injury, which may not be related to toxic effect of dyes used. One should therefore avoid stripping the peripheral ILM outside the macular region to prevent inadvertent retinal damage.