摘要： Dry eye (DE) causes irregularity of the ocular surface and reduces the quality of vision. An intact, regular tear ?lm is essential for high-quality retinal images; however, visual tasks requiring sustained gazing can disrupt the tear ?lm, eventually degrading visual function. A functional visual acuity (FVA) measurement system has been uniquely developed in Japan to evaluate visual function related to tear stability in patients with DE. FVA has been shown to correlate with optical quality. The system measures the change in visual acuity (VA) over time automatically in aqueous-de?cient DE and short tear breakup tear ?lm DE characterized by decreased tear stability and minimal epithelial damage. It is also useful to detect minimal visual deterioration correlated with minimal ocular surface abnormality and vision-related quality of life otherwise undetectable by conventional VA testing, to assess and quantify vision-related symptomatology, and to determine the ef?cacy of treatments for DE disease. Recently, its use has been expanded, such as for the analysis of visual function accompanying lens, cataract and cataract-related disease, retinal disease, refractive surgery, contact glaucoma, amblyopia, presbyopia, and vehicle driving. Its use has revealed that FVA re?ects not only visual function related to tear dynamics, but also visual function related to quick recognition of the target. This simple, noninvasive, and sensitive FVA measurement system may be expected to be used worldwide.