Morphological alternation and influence of aqueous flare in idiopathic epiretinal membrane

Idiopathic epiretinal membrane (iERM) is a common retinal disease in the elderly population. The exact pathogenesis of iERM is unknown. The present study aimed to evaluate the relationship between aqueous flare and morphology of iERM using swept-source optical coherence tomography (OCT).

A consecutive series of 36 eyes of 33 patients with iERM and 109 control eyes of 109 patients were retrospectively examined. Aqueous flare measurements and OCT images were obtained on the same day. The average total retinal, inner retinal, outer retinal, and choroidal thicknesses were calculated using the thickness map mode with an Early Treatment Diabetic Retinopathy Study nine-zone grid that was divided into three zones. The maximum depth of the retinal folds in iERMs was manually measured. The correlation among flare value, maximum depth of folds, and retinal and choroidal thicknesses was evaluated. The morphological changes between the control eyes and the eyes with iERM in different stages were examined.

The result demonstrated a significant positive correlation between the aqueous flare value and total and inner retinal thicknesses in the early stage of iERM. There was a significant positive correlation between the maximum depth of folds and total and inner retinal thicknesses in the early stage of iERM, and the maximum depth of folds significantly increased in the advanced stage. The total and inner retinal thicknesses and proportion of inner retinal thickness significantly increased as the stage of iERM progressed.

The aqueous flare value was associated with retinal thickness in the early stage of iERM, which supports the idea that inflammation or breakdown of blood-ocular barrier is involved in the process of iERM formation. The maximum retinal folds increased as the stage of iERM progressed and retinal thickness increased, which indicates that the tangential force increases as the iERM stage progresses.