What is considered legally blind? 1 answer | Last updated: Apr 03, 2013 Q An anonymous caregiver asked... I'm 43 years old and have recently gotten glasses. The doctor said I am near-sighted and also have astigmatism. My vision is 20/50, 20/50. What does this mean and what is considered legally blind? Thank you, Teres Answers Lylas Mogk, M.D.Caring.com Expert A Lylas Mogk, M.D. is an ophthalmologist and director of the Henry Ford Visual Rehabilitation and Research Center in Grosse Pointe and Livonia, Michigan, and... See full bio 50% helpful Lylas Mogk, M.D. answered... The Social Security Administration defines "legally blind" as either visual acuity in both eyes of less than 20/100 or a horizontal visual field in both eyes of 20 degrees or less. Recommended for You Eye Exams for Older Adults How can I persuade my dad to be honest with others about his vision problem? What's an Amsler grid? What Are Cataracts?