To evaluate the relationship between retinal dot hemorrhage that occurred during membrane peeling (MP) and the damage to the internal limiting membrane (ILM) at idiopathic epiretinal membrane (ERM).

The authors of the present study retrospectively reviewed 50 eyes of 50 consecutive patients who underwent vitrectomy with MP for idiopathic ERM. For all the patients, the ILM was stained with indocyanine green following MP. ILM damage was evaluated using microscopy during the operation. Tissue was examined by light and electron microscopy. Whether or not retinal hemorrhage occurred during the MP and the location of the hemorrhage were also investigated.

During the MP for idiopathic ERM, ILM damage was observed in 43 (86%) of 50 eyes, and some defects of the ILM due to simultaneous removal with the ERM were observed in 37 (74%) of 50 eyes. Retinal dot hemorrhage occurred during the MP in 32 eyes (64%) and did not occur in 18 eyes (36%). In 32 eyes with retinal hemorrhage, ILM damage was observed in 30 eyes (94%). Large or small defects of the ILM due to simultaneous removal with the ERM were observed in 27 of 30 eyes, and ILM tear was observed in 3 eyes. The hemorrhage occurred in 2 eyes without gross ILM damage during the MP. Among 18 eyes without retinal hemorrhage, large or small defects of the ILM due to simultaneous removal with the ERM were observed in 10 eyes (56%). ILM tear was observed in 2 eyes, ILM detachment was observed in 1 eye, while ILM remained intact in 5 eyes (28%). The number of eyes where both ERM and ILM were peeled simultaneously was significantly higher in the cases with retinal hemorrhage ( p = 0.047). Cases of hemorrhage in Gass grade 2 were statistically higher than that in Gass grade 1 ( p = 0.015). OCT type of ERM did not have significant correlation with retinal hemorrhage or ILM damage during the MP.

During the MP for idiopathic ERM, ILM damage was observed in 86% of patients, and some defects of the ILM due to simultaneous removal with ERM were observed in 74% of patients. It is highly suggestive that ILM is damaged at the hemorrhage site if retinal dot hemorrhage occurred during the MP for idiopathic ERM.