AIM: To assess the visual electrophysiological outcomes in children with functional amblyopia who exhibited poor response to conventional treatment. METHODS: Twenty-one children with functional amblyopia, aged 5.7±2.1y (range: 4-10y), underwent comprehensive ophthalmic and refractive evaluations. Spectral domain-optical coherence tomography (SD-OCT) and multifocal electroretinography (mfERG) were conducted to analyze the macular retinal thickness and the first-order response P1 ring of the mfERG in the amblyopic eye (AE) compared to the fellow good eye (GE). RESULTS: Initially, visual acuity in the AE ranged from 20/800 to 20/40, while the GE exhibited a range of 20/25 to 20/20 (P<0.01). After 6mo of treatment, 17 patients demonstrated improved visual acuity in the AE to 20/50 or better, while 4 children showed no improvement. SD-OCT revealed comparable macular and optic disc structures between the AE and GE. Prior to treatment, the mfERG P1 ring amplitude was significantly reduced in the AE compared to GE (P<0.05). The AE/GE ratio of P1 ring amplitude showed significant improvement post-treatment. However, a smaller AE/GE ratio before treatment was associated with poorer improvement post-treatment. CONCLUSION: In the management of functional amblyopia, a thorough assessment of amblyopic eye examinations is crucial. Approximately 20% of amblyopic eyes may not achieve significant improvement in visual acuity, despite the absence of detectable organic retinal abnormalities. mfERG may reveal underlying abnormalities. Integrating mfERG into initial assessments or treatment follow-ups can aid in identifying potential hidden retinal defects and predicting the prognosis of the amblyopic eye.