A Pilot Evaluation of On-Road Detection Performance by Drivers with Hemianopia Using Oblique Peripheral Prisms
Figure 1
(a) Press-on 40Δ Fresnel peripheral prism segments in the oblique configuration on the left spectacle lens as fitted for the study to a patient with left HH. The upper prism is base out and base down, and the lower prism is base out and base up, shown with 9 mm interprism separation, providing expansion in the central area of the visual field used when driving (Figure 2(b)). The effect of the lower prism is notable by the apparent shift of the centrally located lower lid margin, iris, and sclera (imaged by the prism segment). The wearer has an uninterrupted binocular view through the central prism-free area of the lens. (b) Higher-power, 57Δ permanent prism glasses in the oblique configuration with 12 mm interprism separation (not used in this study, but now available from Chadwick Optical Inc., White River Junction, VT, USA).
