Purpose: To describe the presence and integrity of the internal limiting membrane (ILM) after removal of the macular epiretinal membrane (ERM) and to investigate the accuracy of tissue identification using surgical dyes when compared to histopathology results.
Methods: Patients with idiopathic ERM were enrolled in a prospective study and randomized to one of two surgical techniques. In one (Group M), only the ERM was deliberately removed and in the other (Group L) the ILM was also removed. Pars plana vitrectomy and extraction of the ERM with trypan blue dye were performed in all patients. The ILM status was assessed with brilliant blue G dye, and in Group L patients, the ILM was then removed. Histopathology was performed on all samples.
Results: Twenty-six patients underwent the study procedure: 11 in the Group M and 15 in the Group L. The patients' median age was 70.65 years (53-81), and the average follow-up was 15.35 months (4.86-25.10). The ILM extraction patterns were as follows: In Group M in block in 8 of 11 patients and partial in 3 of 11 patients; In Group L in block in 9 of 15 patients, partial in 5 of 15 patients and sequential in 1 of 15 patients. In only 3.8% of patients was the ILM intact after ERM removal. Thirty-two surgical samples were analyzed, containing both ERM and ILM, ERM only, or ILM only. In 84.37% of samples, the tissue identification using surgical dyes was consistent with identification according to pathological examination. This consistency was higher still at 96.7% when focused on ILM identification.
Conclusion: It is technically difficult to extract the ERM in isolation from the ILM. There is good consistency between the content of removed tissue as identified using surgical dyes and the histopathological results of the samples. This is higher in ILM than in ERM.