Our goal is to investigate the application of clinically-practical vision function tests to understanding the relationships between vision function and visual task performance among elders; identifying and monitoring those at risk for vision loss; and suggesting potential interventions for optimizing task performance. In our work to date (in the Smith-Kettlewell Institute or "SKI" Study), we have collected the most complete description ever of changes in vision function with age and their relation to task performance, uncovering new evidence for the importance of "real world" vision function measures that go beyond standard high contrast acuity. We will now examine three major findings more closely. First, we will pursue our discovery that low contrast vision measures are highly predictive of future vision loss in individuals with good high contrast acuity. This finding, with its far-reaching implications, will be closely examined in a longitudinal study incorporating full ophthalmological examinations in addition to our comprehensive vision test battery. Second, we will explore the implications of our discovery that reading rates decline with age even in individuals with good acuity. We will examine the non-acuity and non visual factors in reading performance to improve our understanding of their contributions. Thirdly, we will explore ways in which findings about task performance relating to luminance and binocularity can be exploited to improve reading and face recognition performance among elders with mild to moderate visual impairments. In the process, we will gather two more rounds of data for our longitudinal study, which will then encompass five test points over 15 years, significantly increasing its value and predictive power.