Journal: Optometry and Vision Science

Article Title: Photographic Depiction of the Field of View with Spectacles-mounted Low Vision Aids

doi: 10.1097/OPX.0000000000001790

Figure Lengend Snippet: Field diagrams and percept diagrams. (A) Calculated monocular (left eye) field diagram of a patient with left homonymous hemianopia wearing 57Δ horizontal peripheral prisms. The field diagram illustrates two 30° wide by 20° high segments in the blind field (shifted view) made visible by the peripheral prism. The apical scotoma is also visible in the field diagram as unseen areas within the right, seeing, visual field. (B) Percept diagram (a calculated view of a polar perimetry grid observed by the patient through the device) simulates the retinal image with the peripheral prisms. Apical scotoma is invisible here and only notable as discontinuity between views inside and outside the peripheral prisms. (C) Calculated percept diagram considering additional effects, such as distortions (minification) and dimming of the shifted view.

Article Snippet: The spectacles holder was used to photographically depict the field of view with conventional 57Δ (30° image shift) Fresnel peripheral prisms (Chadwick Optical, Harleysville, PA) in horizontal (Figs. A, B) and oblique configurations (Fig. C)., The interprism separation between upper and lower peripheral prisms was 10 mm.

Techniques:

Journal: Optometry and Vision Science

Article Title: Photographic Depiction of the Field of View with Spectacles-mounted Low Vision Aids

doi: 10.1097/OPX.0000000000001790

Figure Lengend Snippet: A 3D-printed spectacles holder that keeps the spectacles lens 17 mm ( e ) from the camera entrance pupil. The frame's brow bar and bridge position can be adjusted to align the optical centers of the spectacles' lens and the camera lens. Front view (A) and side view (B) of horizontal peripheral prisms (57Δ) glasses mounted on the camera and oblique peripheral prism configuration (C). Enlarged prisms are shown in the insets.

Article Snippet: The spectacles holder was used to photographically depict the field of view with conventional 57Δ (30° image shift) Fresnel peripheral prisms (Chadwick Optical, Harleysville, PA) in horizontal (Figs. A, B) and oblique configurations (Fig. C)., The interprism separation between upper and lower peripheral prisms was 10 mm.

Techniques:

Journal: Optometry and Vision Science

Article Title: Photographic Depiction of the Field of View with Spectacles-mounted Low Vision Aids

doi: 10.1097/OPX.0000000000001790

Figure Lengend Snippet: Photographic depiction with 57Δ Fresnel horizontal peripheral prisms for left homonymous hemianopia (only left lens). Panoramic images of the walking scenario with colliding pedestrians approaching at bearing angles of 15 (A) and 30° (B). The effect of horizontal peripheral prisms with pedestrians at bearing angles of 15° (C to F) and 30° (G to J) shows the shifted view and the apical scotoma (not visible but notable as missing legs of the folding chair on the right side). F numbers were varied from f/2.8 (C, G) to f/5.6 (D, H), and f/8 (E, I) covering the range of the human eye's pupil, and f/22 (F, J) representing the view with a pinhole camera. Details are shown here and not available in the field diagram, including the stronger minification close to the total internal reflection boundary (see the thinner legs of the 30° pedestrian in the shifted view), the limited eye scanning range due to the total internal reflection (the boundary with the hazed area at about 5° into the blind side), the total internal reflection and spurious reflections (multiple lateral mirror images of the ceiling lights, in the upper prism segment), multiplexing effects at the prisms' horizontal boundaries (superimposed shifted and normal views) and multiple prism apertures (smoothed from pinhole results in F, J), and varying levels of scattering from the bases of Fresnel prism (less visible scattering in narrower pupil). The effects on the blind side are only visible when the patient scans into the blind side with the eye. The upper horizontal prism does not capture colliding pedestrians.

Article Snippet: The spectacles holder was used to photographically depict the field of view with conventional 57Δ (30° image shift) Fresnel peripheral prisms (Chadwick Optical, Harleysville, PA) in horizontal (Figs. A, B) and oblique configurations (Fig. C)., The interprism separation between upper and lower peripheral prisms was 10 mm.

Techniques: Multiplexing

Journal: Optometry and Vision Science

Article Title: Photographic Depiction of the Field of View with Spectacles-mounted Low Vision Aids

doi: 10.1097/OPX.0000000000001790

Figure Lengend Snippet: Photographic depiction of the effect of 57Δ oblique peripheral prisms (25° oblique tilt) for left homonymous hemianopia (left lens only). (A) Calculated field diagram using a pinhole camera model. Lateral 27° wide segments of the blind field above and below the horizontal midline are made visible. Small diplopia occurs around the apex of the oblique peripheral prisms. Photographic depiction of the oblique peripheral prism effects with 15 (B to E) and 30° (F to I) pedestrians (illustrated in Figs. A and B, respectively) is demonstrating both laterally and vertically shifted views and actual rendition of the apical scotoma (invisibility of the folding chair legs in the right side). Small diplopic areas are illustrated twice in both inside and outside of the oblique prisms. Both the upper and lower oblique prisms image the 15° pedestrian when the camera is aimed straight ahead. However, because of the reduced lateral prism power, only part of the right leg of the 30° pedestrian is seen in the lower segment. F number was varied from f/2.8 (B, F), f/5.6 (C, G), and f/8 (D, H) covering the range of the human eye and f/22 (E, I) for the pinhole camera. The gap between the upper and lower prisms is affected by the pupil size. Note the more visible shoulders and neck of the pedestrian in the leftmost column (f/2.8) than the third column (f/8).

Article Snippet: The spectacles holder was used to photographically depict the field of view with conventional 57Δ (30° image shift) Fresnel peripheral prisms (Chadwick Optical, Harleysville, PA) in horizontal (Figs. A, B) and oblique configurations (Fig. C)., The interprism separation between upper and lower peripheral prisms was 10 mm.

Techniques:

Journal: Optometry and Vision Science

Article Title: Photographic Depiction of the Field of View with Spectacles-mounted Low Vision Aids

doi: 10.1097/OPX.0000000000001790

Figure Lengend Snippet: Photographic depiction of 57Δ peripheral prisms for right homonymous hemianopia (photopic outdoor pupil, f/8). (A) Driving scenario with a pedestrian at 10° bearing and 12 m away. (B) The same scene through horizontal peripheral prisms. Neither upper nor lower prism shows any useful field of view for the driving. (C) With oblique peripheral prisms. The lower peripheral prism is still not useful. The upper peripheral prism shifts the pedestrian from the blind side to the seeing side, but the image contrast near the pedestrian location is low. D, The oblique peripheral prisms with the sun visor pulled partially down. The visor improves the contrast of the shifted view.

Article Snippet: The spectacles holder was used to photographically depict the field of view with conventional 57Δ (30° image shift) Fresnel peripheral prisms (Chadwick Optical, Harleysville, PA) in horizontal (Figs. A, B) and oblique configurations (Fig. C)., The interprism separation between upper and lower peripheral prisms was 10 mm.

Techniques: