To evaluate the impact of the age of onset of low vision on patients' vision-related quality of life (VR-QoL) and mental health. Low-vision patients who visited Chung-Ang University hospital from January 2012 to December 2014 were included. Patients were divided into the congenital low-vision (CLV) and acquired low-vision (ALV) groups according to the age of disease onset. People with normal visual function comprised the control group. VR-QoL was estimated with the National Eye Institute Visual Function Questionnaire (NEI VFQ-25), while mental health was assessed through the Beck Depression Inventory (BDI) and the Beck Anxiety Inventory (BAI). The mean scores of each questionnaire were compared between the groups in independent t-tests. Overall, 125 low-vision patients (55 CLV and 70 ALV) and 71 control subjects were included. Although the subscale and composite scores of the NEI VFQ-25 were lower in the ALV group than in the CLV group, the differences were not significant. However, the BDI and BAI scores were significantly higher in the ALV group than in the CLV group (12.07 ± 11.97 vs. 7.67 ± 9.04, P = 0.021; 9.11 ± 10.51 vs. 5.69 ± 6.85, P = 0.030, respectively). Also, the number of patients requiring expert consultation for depression was higher in the ALV group than in the CLV group (P = 0.010). ALV patients have more vulnerable mental health states than CLV patients. Therefore, assessment of the age of onset of low vision and mental health plays a critical role in successful rehabilitation.