Keywords:
Aid to vision, Classification, Classifying (documents), Colour, Definitions, Enlarging, Filters, Handicapped people, Magnifiers, Marking, Mechanic, Ophthalmic equipment, Ophthalmic optics, Ophthalmology, Optical, Optical equipment, Optical instruments, Optics, Parameters, Picture shifts, Ratings, Specification (approval), Spectacles (eyeglasses), Telescopes, Testing, Visual acuity, Visual field, Weak-sighted people