Ключевые слова: accuracy, aid, alphabet, background, black, business, chart, closeup, concepts, differential, doctor, effort, equipment, exam, eye, eyesight, eyewear, glass, glasses, healthcare, human, improvement, letter, life, loop, magnifier, magnifying, medical, medicine, nobody, office, optical, optician, optometrist, part, patient, people, perception, person, selective, sensory, sight, snellen, test, text, transparent, typescript, visual, western,