Patients With Homonymous Hemianopia Become Visually Qualified to Drive Using Novel Monocular Sector Prisms

Abstract

Patients with homonymous hemianopia (HH) often fail to meet visual field (VF) requirements for a driver's license. We describe 2 patients with complete HH, who met the minimum VF requirements for driving using a novel, high-power, monocular sector prism system. Baseline VFs were assessed using automated and kinetic perimetry. Patients were fitted with glasses and press-on 57-PD peripheral monocular sector prisms placed on the lens ipsilateral to the VF defect above and below the visual axis with prisms oriented obliquely. Kinetic perimetry was reassessed both monocularly and binocularly, with and without prisms. The 2 patients had 95° and 82° angle of continuous, horizontal, binocular VF. With the use of the prism system, the binocular VF increased to 115° and 112° angles. Both patients reported improvement in quality of life and each holds a valid driver's license and has successfully operated a motor vehicle without any restrictions or accidents. These findings suggest that the addition of oblique 57-PD prisms to the ipsilateral spectacle lens above and below the visual axis for patients with complete HH can significantly increase horizontal VF, which may help an individual become visually qualified to obtain a driver's license.

Homonymous hemianopia: challenges and solutions

“… 39 The increase in visual field obtained with 57 prism diopter obliquely placed prisms may allow patients with complete HH to drive legally in some states. Moss et al 53 found an increase in the binocular field from 95° to 115° in one patient and from 82° to 112° in another patient. This would be sufficient to drive in over half of the states in the US.…”

Driving with homonymous visual field loss: a review of the literature

“…The early results of a driving simulator study of the oblique prisms (57 Δ rigid Fresnel) are also promising; detection rates for pedestrian hazards on the affected side are better with than without the prism glasses . A recent case study reported two young patients (24 and 31 years) with acquired hemianopia, who were fitted with oblique peripheral prisms (57 Δ rigid Fresnel). Both were licenced to drive in Minnesota (field extent requirement 105 degrees) and had operated a motor vehicle without any restrictions or accidents for one and five years, respectively, at the time the report was written.…”

Should Visual Restoration Therapy be Used in Patients With Visual Field Loss?

“…The final option, which is the best as far as I am concerned, is to use monocular sector prisms. These prisms are effective at all gaze angles (26,27).…”