Fusion and Suppression in Patients with Unilateral Idiopathic Epiretinal Membrane

Purpose: To investigate the presence of fusion and suppression in patients with unilateral idiopathic epiretinal membrane (ERM). Methods: Thirty-five patients with unilateral idiopathic ERM received a full ophthalmologic exam including best corrected visual acuity (BCVA). Patients were divided into suppression and non-suppression groups according to the results of 4 Prism Dioptre Base-out Test and Worth 4 Dot test. Age, symptoms, duration of ERM, BCVA, average M-chart score, results of Titmus test and optical coherence tomography parameters were compared between the two groups. Factors associated with suppression were also evaluated. Results: Eleven (31%) of 35 patients had suppression. The BCVA (0.18 +/- 0.12 vs. 0.29 +/- 0.12 p = 0.019) and stereopsis (2.25 +/- 0.27 vs. 2.66 +/- 0.62, p = 0.009) were significantly lower in the suppression group than the non-suppression group. Median age was older (63.21 +/- 9.64 vs. 70.82 +/- 6.80, p = 0.013) and duration of ERM (7.86 +/- 3.69 vs. 18.54 +/- 14.92 months, p = 0.004) was longer in the suppression group than the non-suppression group. Average M-chart score was higher in the suppression group. However, not all the patients suffered from metamorphopsia, including the suppression group when using binocular vision. Conclusions: Unilateral suppression is common in unilateral idiopathic ERM and influences the patient's stereopsis. Suppression was significantly correlated with age, duration of symptoms and metamorphopsia.