Parameters in the use of CCTV's and optical aids.

Data from 96 veterans who had been using a closed circuit television (CCTV) for at least 2 years are presented. Most patients (87%) reported continuing use of the CCTV and demonstrated their proficiency in its use. Fifty percent of all patients used an optical aid, as well as a CCTV for near work. These patients did not differ on mean reading speeds for either type of aid, but the CCTV did provide significantly longer reading durations. Neither near nor far visual acuity measures were correlated with performance variables. Linear magnification, working distance, and effective magnification on the CCTV appeared to interact to influence CCTV reading speed. The data have clear implications for clinical practice.