Sioux Falls Rehabilitation Center for the Blind student, Trenton Rowland, 28, of Sheridan, Wyo., who has retinitis pigmentosa--a degenerative eye disease that causes severe vision impairment and often blindness--adjusts the height of a table saw blade using his hands to make sure he's adjusting it enough while Bob Smith, an orientation and mobility and home mechanics and creative arts instructor at the Rehabilitation Center, holds onto the lumber while working in the wood shop on Thursday, April 10, 2014, at the South Dakota Rehabilitation Center for the Blind in Sioux Falls. (Joe Ahlquist / Argus Leader)