[Computer-based assessment of visual acuity--technical realization]

Testing of visual acuity for distant vision can be computerized by using monitor screens to present optotypes. Because of the limited spatial resolution of conventional monitors, measurement of visual acuity for near vision is not possible. This paper describes a new computer-aided method for the measurement of both near and distant visual acuity. Our approach to the assessment of visual acuity for near vision is based on a recently developed liquid crystal display (a screen, LCD) measuring 10.5 mm x 15 mm. The LCD permits the presentation of optotypes for the measurement of visual acuity between 0.063 and 1.25 at a viewing distance of 40 cm (near/distant). The presentation of optotypes for the assessment of the acuity of distant vision uses a standard 17" monitor that permits visual acuity figures of between 0.032 and 1.6 to be assessed.