Background: The present study examined the relationships among retinal structure, peripheral retinal abnormalities, and epiretinal membrane (ERM) and explored the utility of ultra-wide-field laser scanning ophthalmoscopy in idiopathic ERM assessment. Methods: The study sample comprised 276 eyes of 276 patients. Ultra-wide field fundus imaging was performed without mydriasis using Optos California. Each patient underwent a Goldmann three-mirror contact lens fundus examination. Results: Ultra-wide field laser scanning ophthalmoscopy revealed peripheral retinal degeneration in 84 (54.54%) eyes in the ERM and in 28 (22.95%) eyes in the control group. Goldmann three-mirror contact lens examination revealed peripheral retinal degeneration in 96 (62.33%) eyes in the ERM group and 42 (34.42%) eyes in the control group. Ultra-wide field ophthalmoscopy enabled the detection of nearly 87% of all peripheral retinal lesions in patients with ERM, but it cannot replace fundus examination with a Goldmann triple mirror or ophthalmoscopy with scleral indentation. Conclusions: In most patients, idiopathic ERM coexisted with changes in the peripheral retina. Some of these changes promote retinal detachment. Thus, surgeons should consider the risk of retinal tear during vitrectomy, which increases the scope of surgery and may adversely affect prognosis. Although ultra-wide field imaging is a valuable diagnostic method, it is not a substitute for Goldmann three-mirror contact lens fundus examination or ophthalmoscopy with scleral indentation.