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N Usumoto, M Arai, K Fujita, HM Cheng, T Hirose; An Efficacy and Eligibility Study of Portable Closed-Circuit Television as a Low-Vision Aid . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3831.
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Purpose:To analyze the efficacy of a portable closed-circuit television (P-CCTV) as a low vision aid. Emphasis is on formulation of selection criteria, or eligibility, based on visual acuity and age. Methods:The P-CCTV consisted of a head-mounted LCD goggles coupled to a pencil-type micro charge couple device (CCD) camera. The contrast and the polarity of the displays were both adjustable. Patients whose distance visual acuity (VA) was 20/200 or worse in the better eye were tested. 101 patients (46 males, 55 females; age 4-93) entered the study. Continuous Text Card and MNRead charts were used in this study. We compared VA with the P-CCTV with that with a 10X stand-magnifier in order to determine the threshold visual acuity that could be enhanced by the P-CCTV. In addition, improvement of reading acuity with the P-CCTV was analyzed according to the patients' ages. Results:Overall, the mean distance VA was 0.062 (1.37 logMAR), whereas the mean acuity with the P-CCTV was 0.580 (0.50 logMAR). In 36 patients who tried both the P-CCTV and the 10X magnifier, the acuity was better with an average of 0.33 logMAR with the CCTV. Patient's age: The subjects were divided into 5 age groups in 20-year increments from 0-100 years. In all groups, the vision was increased by using P-CCTV. The middle-aged group (40-59 y.o.) performed the best with up to 0.720 (0.232 logMAR) acuity. The very young, however, responded the least, to only 0.420 (0.990 logMAR). Minimal acuity: The distance VA in the better eye that could be improved more than 1.0 logMAR with P-CCTV ranged from 20/200 (1.0 logMAR) to HM. VA for near that could be improved more than 0.4 logMAR with P-CCTV ranged from 20/63 (0.5 logMAR) to LP. Six patients with profound loss of vision who could not read with the P-CCTV were all younger than 25 y.o. (mean 10.8), and 5 of them could not read with the 10X magnifier. Patient's impression: Overall, 70.3% of the patients stated that they wanted to use P-CCTV as a low vision aid. Satisfaction in the very young (0-19 y.o.) was higher (65.5%) than that in the very old (80-99 y.o.) (57.9%). Conclusion:The head-mounted P-CCTV appears beneficial for many low-vision patients, especially for adults aged from 40-59 y.o. A number of patients with vision as poor as HM and who could not read with a 10X optical magnifier were able to read letters with the P-CCTV.
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