Ключевые слова: acuity, astigmatism, background, bifocal, black, chart, closeup, concept, conceptual, corrective, crystal, distance, eye, eyestrain, farsightedness, frame, glasses, horn, lens, lenses, long sightedness, looking, medicine, myopia, myopic, nearsightedness, object, oculist, ophthalmologist, ophthalmology, optical, optics, optotypes, plastic, rimmed, see, seniors, short, short sightedness, shortness, sight, sign, snellen, spectacles, symbol, vertical, vision, visual, white,