Purpose: The Collaborative Longitudinal Evaluation of Keratoconus Study (CLEK) previously showed that people with keratoconus report significantly impaired vision-related quality-of-life (V-QoL), as measured on the National Eye Institute Visual Function Questionnaire (NEI-VFQ), similar to that of people who have severe macular degeneration. For this study, we evaluated changes that occurred in V-QoL over seven years of follow-up. Design: In this prospective cohort study of 1,166 participants followed up for seven years, we estimated change in V-QoL by projecting the slope of a minimum of three reports on 11 scales of the NEI-VFQ. Correlation with clinical indicators was evaluated, and differences were assessed between those who had clinically significant changes in clinical factors and those who did not. Logistic regression was used to assess factors associated with a decline in 10 points or more in a scale score over seven years. Results: All scales showed modest decline except ocular pain and mental health. Baseline factors were not associated with longitudinal change in NEI-VFQ scores. A 10-letter decline in high-contrast binocular visual acuity or a 3.00-diopter increase in corneal curvature were associated with significantly larger declines in V-QoL. In multivariate analysis, these factors also were found to be associated with a 10-point decline in NEI-VFQ scale scores. Conclusions: Keratoconus is associated with significantly impaired V-QoL that continues to decline over time. For a substantial plurality of patients, these declines are significant.