EDTs are fundamental to the diagnosis and phenotyping of many acquired retinal and visual pathway disorders. They also provide methods for the objective assessment of the efficacy and safety of potential novel treatments across short periods. Conventional psychophysical tests, such as visual acuity, are of limited value in localizing and characterizing dysfunction and are not always suitable for monitoring purposes. This review highlights where EDTs may address the need for better outcome measures to evaluate novel treatments within clinical trials, helping to select early treatment candidates and for the assessment of safety and efficacy.