American Family Physician. https://www.aafp.org/afp/1999/0701/p99.html
Diakses pada 9 April 2019Cleveland Clinic. https://my.clevelandclinic.org/health/articles/8567-common-aged-related-eye-problems
Diakses pada 9 April 2019WebMD. https://www.webmd.com/eye-health/vision-problems-aging-adults#1
Diakses pada 9 April 2019All About Vision. https://www.allaboutvision.com/over60/ways-to-protect.htm
Diakses pada 9 April 2019