Purpose. We evaluated whether a functional visual acuity (FVA) system can detect subtle changes in central visual acuity that reflect pathological findings associated with age-related macular degeneration (AMD). Methods. Twenty-eight patients with unilateral AMD and logMAR monocular best corrected VA better than 0 in both eyes, as measured by conventional chart examination, were analyzed between November 2012 and April 2013. After measuring conventional VA, FVA, and contrast VA with best correction, routine eye examinations including spectral domainYoptical coherence tomography were performed. Standard Schirmer test was performed, and corneal and lens densities were measured. Results. The FVA score (p G 0.001) and visual maintenance ratio (p G 0.001) measured by the FVA system, contrast VA (p G 0. 01), and conventional VA (p G 0.01) were significantly worse in the AMD-affected eyes than in the fellow eyes. No significant differences were observed in the anterior segment conditions. Forward stepwise regression analysis demonstrated that the length of interdigitation zone disruption, as visualized by optical coherence tomography imaging, correlated with the FVA score (p G 0.01) but not with any other parameters investigated. Conclusions. The FVA system detects subtle changes in best corrected VA in AMD-affected eyes and reflects interdigitation zone disruption, an anatomical change in the retina recorded by optical coherence tomography. Further studies are required to understand the value of the FVA system in detecting subtle changes in AMD. (Optom Vis Sci 2016;93:70Y76) Key Words: functional visual acuity, interdigitation zone, optical coherence tomography, age-related macular degeneration, retina R ecent progress in medical technology and science has facilitated the development of effective treatments for retinal diseases, such as molecular targeted drugs, and antiYvascular endothelial growth factor (anti-VEGF) drugs for age-related macular degeneration (AMD), as well as pars plana vitrectomy. With the improvement in prognosis, treatment is extended to patients who have better visual function at baseline. Thus, a sensitive method for detecting subtle changes in central visual acuity (VA) that reflects pathological findings of AMD and other retinal diseases is warranted. One method proposed for this purpose is the functional VA (FVA) system. The FVA system can detect subtle visual dysfunction caused by epiretinal membrane in eyes with good VA as measured by conventional Landolt C charts.1 However, whether this method is able to detect the subtle impairment of visual function caused by AMD and reflect the retinal clinical findings remains obscure.The FVA system uses a series of charts shown continuously and requires patient responses within 2 s of each chart display, which is in contrast to the conventional Landolt C chart examination, in which patients can stare at the chart before responding. Contrast VA testing involves the use of a lower-contrast Landolt C chart than conventional VA measurement, but...