Indocyanine green-assisted peeling of the internal limiting membrane in macular hole surgery affects visual outcome: a clinicopathologic correlation

Abstract

Purpose To report the ultrastructure of the internal limiting membrane (ILM) after macular hole surgery with indocyanine green (ICG) staining and to investigate an association with the postoperative functional outcome. Design Retrospective, noncomparative analysis of a consecutive case series. Methods Twenty eyes of 20 patients after macular hole surgery with ICG staining were included. Visual acuity and Goldmann perimetry were obtained before and after surgery. The ILM was obtained during three-port pars plana vitrectomy for idiopathic macular hole. Twenty-five milligrams of sterile ICG powder was dissolved in 5 ml of sterile water as recommended by the manufacturer and then diluted in balanced salt solution. The ultrastructure of the ILM was analyzed using light and transmission electron microscopy. Osmolarity and pH of the ICG solution were measured preoperatively. Results There was no statistically significant improvement of postoperative visual acuity after ICG-assisted peeling ( P = .755). In seven patients, postoperative visual field defects occurred. Indocyanine green-stained specimens revealed cellular elements resembling the plasma membrane of Müller cells and other undetermined retinal structures adherent to the retinal side of the ILM. Histologic findings disclosed no difference between patients with and without visual field defects after the use of ICG. The osmolarity of the ICG solution applied was 275 mOsm; pH was 7.5. Conclusions Intravitreal application of ICG may cause retinal damage by altering the cleavage plane to the innermost retinal layers. That may result in less improvement of visual acuity and unexpected visual field defects. The underlying mechanisms of action remain unclear and are the subject of ongoing investigations.