ILM REMOVAL

Dye helpful in ILM peeling, study finds

Staining of the inner limiting membrane (ILM) using a latest-generation dye seems to provide a safe and more effective means of removing the membrane in vitreoretinal surgical procedures, according to Yannick Le Mer MD. “Do we need dyes for ILM peeling? The answer is undoubtedly yes if we want to be sure that we have removed everything. It is the only objective way to assess peeling quality. It makes ILM removal safer and it is easier to remove something that you can actually see than something which is supposed to be there but is difficult to identify clearly,†Dr Le Mer told delegates attending the 11th EURETINA Congress.

Explaining the rationale for his study, Dr Le Mer, an ophthalmologist at the Fondation Rothschild in Paris,  France, said that while ILM is routinely removed during macular surgery, it is not always clear if the procedure is useful, safe and complete for all patients.

“The use of dyes has been proposed as a means to improve visualisation, safety, and the quality of ILM removal. We wanted to see if that is the case and what might be the best way to assess these improvements,†he said. Dr Le Mer’s prospective study included a total of 70 patients undergoing vitrectomy for macular epiretinal membrane in 36 cases, vitreomacular traction syndrome in 19, idiopathic macular holes in 11 patients and diabetic macular oedema in four cases.

“The idea was to perform vitrectomy with ILM peeling without dye, then with injection of dye to assess the quality of ILM removal, and then to repeat the ILM dissection if needed. The primary endpoint of the study was the number of cases with an incomplete dissection and the secondary endpoint was the number of peeling-related complications before and after staining,†said Dr Le Mer.

Patients excluded were those with highly myopic foveo-schisis and those who had undergone previous ocular surgery even if the ILM had been left intact.

In choosing the most appropriate dye for the study, Dr Le Mer and colleagues (Drs Devin, Morel and Morin, Clinique Monticelli in Marseille, France) opted for a relatively new dye, Brilliant Blue (Brilliant Peel, Fluoron GmbH). The dye is supplied ready for injection in a vial and does not require mixing before use. After vitrectomy the dye is injected over the macular area without the need to perform a fluid-air exchange.

“We opted for Brilliant Blue because it was the only dye with a CE marking specifically for ILM peeling when the study began. It is widely used in the food industry and has no known clinical toxicity. Indeed some studies have shown that it may even have some beneficial effects on neural tissue with only minimal side effects,†he said.

Looking at the results, Dr Le Mer noted that it was necessary to peel the ILM again in 38 per cent of cases, with cosmetic peeling necessary in 20 per cent of patients and no further peeling required in 42 per cent. The indications seemed to have a bearing on the necessity for re-peeling, with an even distribution of epiretinal membranes requiring a second attempt compared to all four cases of diabetic macular edema.

Complications were also more common without staining. In 33 per cent of the eyes, either retinal pinches or localised superficial haemorrhages occurred, and were practically eliminated after staining.

Dr Le Mer said that the clear conclusion was that using dyes for ILM removal was definitely beneficial. “I think this is purely down to better visualisation of the ILM using the dye rather than any positive biological effect of the dye on the adherence of the tissue to the retina,†said Dr Le Mer.

Another benefit is that the use of staining actually speeds up the overall surgery time, he said. “After vitrectomy and the direct injection of Brilliant Blue after infusion closure, the removal of the dye is very fast and only takes about 30 seconds,†he said.
The only real downside of using Brilliant Blue, said Dr Le Mer, is the cost. “It is an expensive product and the price is too high.

However, this is really the only viable argument for continuing with indocyanine green (ICG) use bearing in mind concern about its possible phototoxicity and the fact that there is no CE mark for ICG either,†he said. Dr Le Mer added that staining is mandatory when the surgeon needs to completely remove the ILM.

“Studies comparing surgical outcomes with or without ILM peeling should always use a specific dye in order to properly assess the outcomes. Brilliant Blue is expensive but it is the only dye with CE marking which helps to avoid any possibility of a ‘kitchen pharmacy’ approach to its use in surgery,†he said.