Task performance with the Low Vision Enhancement System (LVES)

Author： Weckerle P. Trauzettel-Klosinski S. Kamin G. Zrenner E.

ISSN： 1388-235X

Source： Visual Impairment Research, Vol.2, Iss.3, 2000-12, pp. : 155-162

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Abstract

Purpose: To evaluate task performance with the Low Vision Enhancement System (LVES) in patients with central scotoma with regard to daily living activities such as reading, writing, and mobility as well as contrast sensitivity. Patients and Methods: Seventeen patients (aged 17-85 years, mean 49 ± 21) were examined with the LVES, a head-mounted opto-electronic visual aid that provides focus at various distances, a magnification from 1.5 to 12 times, and contrast enhancement. First, visual acuity and magnification need were determined without the device. Then, after individual adjustment of the LVES, the performance of different tasks was evaluated using the system, and assessments were made in a semiquantitative manner. Contrast sensitivity was measured using Pelli-Robson charts with and without the contrast enhancement function of the LVES. Results: Reading was fluent without mistakes in 10 patients, hesitating without mistakes in three, and struggling with mistakes in one. Three patients were unable to read. Patients with a higher magnification requirement (≥8×) had a considerably reduced reading ability. Handwriting was legible in six patients, shaky in seven, and illegible in one. With regard to mobility, five patients had no problems walking, seven had minor problems, two had trouble using the stairway, and one was very insecure while walking. Contrast sensitivity was improved in all patients (2-6 steps) using the contrast enhancement. Conclusion: The LVES is a useful visual aid for patients with a central scotoma and a magnification need of <8×, if they have a need for continuous adaptation to different working distances, a working distance exceeding the range of optical aids, a manual task requiring both hands free, or a need for system mobility.