Non-optical aids.
D001877:Books; D005139:Eyeglasses; D005374:Filtration; D006801:Humans; D008029:Lighting; D009885:Ophthalmology / Q000295:instrumentation; D011327:Printing; D012682:Sensory Aids; D014786:Vision Disorders / Q000628:therapy*; D014792:Visual Acuity