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A pilot evaluation of on-road detection performance by drivers with hemianopia using oblique peripheral prisms.

Bowers AR, Tant M, Peli E - Stroke Res Treat (2012)

Bottom Line: We conducted a pilot study to evaluate the effects of oblique peripheral prisms, a novel development in optical treatments for HH, on detection of unexpected hazards when driving.Results.Conclusions.

View Article: PubMed Central - PubMed

Affiliation: Schepens Eye Research Institute, Massachusetts Eye and Ear, and Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA.

ABSTRACT
Aims. Homonymous hemianopia (HH), a severe visual consequence of stroke, causes difficulties in detecting obstacles on the nonseeing (blind) side. We conducted a pilot study to evaluate the effects of oblique peripheral prisms, a novel development in optical treatments for HH, on detection of unexpected hazards when driving. Methods. Twelve people with complete HH (median 49 years, range 29-68) completed road tests with sham oblique prism glasses (SP) and real oblique prism glasses (RP). A masked evaluator rated driving performance along the 25 km routes on busy streets in Ghent, Belgium. Results. The proportion of satisfactory responses to unexpected hazards on the blind side was higher in the RP than the SP drive (80% versus 30%; P = 0.001), but similar for unexpected hazards on the seeing side. Conclusions. These pilot data suggest that oblique peripheral prisms may improve responses of people with HH to blindside hazards when driving and provide the basis for a future, larger-sample clinical trial. Testing responses to unexpected hazards in areas of heavy vehicle and pedestrian traffic appears promising as a real-world outcome measure for future evaluations of HH rehabilitation interventions aimed at improving detection when driving.

No MeSH data available.


Related in: MedlinePlus

Binocular visual field (Goldmann V4e) of a patient with left HH (a) without peripheral prisms, (b) with 40Δ oblique peripheral prisms as fitted for this study with no vertical separation between the expansion areas (9 mm interprism separation and 30° angle of tilt), and (c) with the original horizontal design of 40Δ peripheral prisms for walking [21] (12 mm interprism separation). The oblique design provides about 20° of lateral expansion into central areas of the blind hemifield in the region used when looking through a car windshield (rectangle represents the field of view through a typical car windshield for driving on the right [22]); the horizontal design does not provide expansion within this area. Small black squares are the individual points mapped during the perimetry.
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fig2: Binocular visual field (Goldmann V4e) of a patient with left HH (a) without peripheral prisms, (b) with 40Δ oblique peripheral prisms as fitted for this study with no vertical separation between the expansion areas (9 mm interprism separation and 30° angle of tilt), and (c) with the original horizontal design of 40Δ peripheral prisms for walking [21] (12 mm interprism separation). The oblique design provides about 20° of lateral expansion into central areas of the blind hemifield in the region used when looking through a car windshield (rectangle represents the field of view through a typical car windshield for driving on the right [22]); the horizontal design does not provide expansion within this area. Small black squares are the individual points mapped during the perimetry.

Mentions: Peripheral prisms are a recent development in optical treatments for HH [36]. High-powered prism segments placed above and below the primary line of sight on the spectacle lens on the side of the field loss (Figure 1) provide visual field expansion (enlargement of the visual field; Figure 2), which is helpful for obstacle detection when walking [21, 36, 37]. When permanent peripheral prism glasses incorporating 57Δ embedded prism segments are worn (Figure 1(b)), the expansion can extend as much as 30° into the blind hemifield (equivalent to the width of about 6 to 7 lanes of traffic at 50 m). The latest innovation is the oblique design [38] that provides expansion in paracentral areas of the field, in regions used when looking through a car windshield [22] (Figure 2(b)). By comparison, the original “horizontal” design provided expansion only in areas outside the central regions of the field (Figure 2(c)). With the oblique design, although the expansion is in paracentral areas, the prism images fall on more peripheral retina; therefore, central diplopia (double vision) does not occur. Users are taught to always look through the central, prism-free area of the lens and to eye scan as they would do habitually; the visual field expansion is effective at all lateral positions of gaze.


A pilot evaluation of on-road detection performance by drivers with hemianopia using oblique peripheral prisms.

Bowers AR, Tant M, Peli E - Stroke Res Treat (2012)

Binocular visual field (Goldmann V4e) of a patient with left HH (a) without peripheral prisms, (b) with 40Δ oblique peripheral prisms as fitted for this study with no vertical separation between the expansion areas (9 mm interprism separation and 30° angle of tilt), and (c) with the original horizontal design of 40Δ peripheral prisms for walking [21] (12 mm interprism separation). The oblique design provides about 20° of lateral expansion into central areas of the blind hemifield in the region used when looking through a car windshield (rectangle represents the field of view through a typical car windshield for driving on the right [22]); the horizontal design does not provide expansion within this area. Small black squares are the individual points mapped during the perimetry.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3539405&req=5

fig2: Binocular visual field (Goldmann V4e) of a patient with left HH (a) without peripheral prisms, (b) with 40Δ oblique peripheral prisms as fitted for this study with no vertical separation between the expansion areas (9 mm interprism separation and 30° angle of tilt), and (c) with the original horizontal design of 40Δ peripheral prisms for walking [21] (12 mm interprism separation). The oblique design provides about 20° of lateral expansion into central areas of the blind hemifield in the region used when looking through a car windshield (rectangle represents the field of view through a typical car windshield for driving on the right [22]); the horizontal design does not provide expansion within this area. Small black squares are the individual points mapped during the perimetry.
Mentions: Peripheral prisms are a recent development in optical treatments for HH [36]. High-powered prism segments placed above and below the primary line of sight on the spectacle lens on the side of the field loss (Figure 1) provide visual field expansion (enlargement of the visual field; Figure 2), which is helpful for obstacle detection when walking [21, 36, 37]. When permanent peripheral prism glasses incorporating 57Δ embedded prism segments are worn (Figure 1(b)), the expansion can extend as much as 30° into the blind hemifield (equivalent to the width of about 6 to 7 lanes of traffic at 50 m). The latest innovation is the oblique design [38] that provides expansion in paracentral areas of the field, in regions used when looking through a car windshield [22] (Figure 2(b)). By comparison, the original “horizontal” design provided expansion only in areas outside the central regions of the field (Figure 2(c)). With the oblique design, although the expansion is in paracentral areas, the prism images fall on more peripheral retina; therefore, central diplopia (double vision) does not occur. Users are taught to always look through the central, prism-free area of the lens and to eye scan as they would do habitually; the visual field expansion is effective at all lateral positions of gaze.

Bottom Line: We conducted a pilot study to evaluate the effects of oblique peripheral prisms, a novel development in optical treatments for HH, on detection of unexpected hazards when driving.Results.Conclusions.

View Article: PubMed Central - PubMed

Affiliation: Schepens Eye Research Institute, Massachusetts Eye and Ear, and Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA.

ABSTRACT
Aims. Homonymous hemianopia (HH), a severe visual consequence of stroke, causes difficulties in detecting obstacles on the nonseeing (blind) side. We conducted a pilot study to evaluate the effects of oblique peripheral prisms, a novel development in optical treatments for HH, on detection of unexpected hazards when driving. Methods. Twelve people with complete HH (median 49 years, range 29-68) completed road tests with sham oblique prism glasses (SP) and real oblique prism glasses (RP). A masked evaluator rated driving performance along the 25 km routes on busy streets in Ghent, Belgium. Results. The proportion of satisfactory responses to unexpected hazards on the blind side was higher in the RP than the SP drive (80% versus 30%; P = 0.001), but similar for unexpected hazards on the seeing side. Conclusions. These pilot data suggest that oblique peripheral prisms may improve responses of people with HH to blindside hazards when driving and provide the basis for a future, larger-sample clinical trial. Testing responses to unexpected hazards in areas of heavy vehicle and pedestrian traffic appears promising as a real-world outcome measure for future evaluations of HH rehabilitation interventions aimed at improving detection when driving.

No MeSH data available.


Related in: MedlinePlus