Sir,

The use of intravitreal triamcinolone to demonstrate areas of undetached vitreous1 has gained in popularity in recent years. The authors have not clarified whether their technique is also applicable for the identification (and removal) of residual or ‘undetached’ posterior hyaloid membrane.

The histology, immunohistochemistry, and ultrastructure of the posterior hyaloid membrane has been extensively described,2, 3, 4, 5, 6 and recent research has highlighted its role in the pathogenesis of many vitreoretinal disorders, including macular holes, cellophane maculopathy, macular pucker, and vitreomacular traction syndrome.4, 5 It has also become clear that the presence or absence of a Weiss ring is insufficient for the diagnosis of complete separation of PHM.4, 5

The authors allude to the possibility of ‘undetached hyaloid fragments’ being related to future epiretinal membrane (ERM) formation, but recent research suggests that the evidence for PHM in this role is particularly strong.5 Incomplete separation of the PHM, rather than the cortical gel it envelops, would explain why seven patients in the study developed ERM without any associated residual vitreous staining (with one developing severe macular pucker).

We support the authors’ proposition that evaluation of the vitreo–retinal relationship in eyes with retinal detachment, ‘even when there is apparent PVD’, is of great clinical importance. However, although triamcinolone acetonide appears helpful in the demonstration of residual cortical vitreous, it is important to recognise that residual vitreous is merely a pointer to an underlying incomplete separation of the posterior hyaloid membrane.