Scanning Training in Neurological Vision Loss Paul Koons, Scott Johnson, John Kingston, and Gregory L. Goodrich, Eye and Brain (page 1 of 6) Page 1 of 6

Multimedia

• 
  Dr. James Kelly is professor of Neurosurgery and Physical Medicine and Rehabilitation at the University of Colorado Denver School of Medicine and associate director of the Colorado Area Health Education Center System. This is BrainLine's exclusive interview with Dr. Kelly recorded on July 11, 2008. Transcript of the program here.
• Dr. James Kelly Talks About Areas of the Brain Affected by Concussion
• 
  This documentary work-in-progress shares poignant stories of people with TBI — from a victim of a road-rage beating to a Marine infantryman returning home wounded from Iraq. From David L. Brown Productions and Epic Way Sports. Used with permission. All rights reserved. Going the Distance is a 26-minute work-in-progress. Learn more about the project and the final documentary: http://www.goingthedistance.info Transcript of this video.
• Going the Distance

Abstract:

The purpose of this paper is to describe the response of a Department of Veterans Affairs medical center’s development of a rehabilitation program for patients with hemianopsia. Hemianopsia affects significant numbers of troops returning from Afghanistan and Iraq and their neurological vision loss presented unique challenges in developing an appropriate and effective rehabilitation program. A literature review indicated that existing therapies lacked supporting scientific evidence and that Traumatic Brain Injury (TBI)-related vision loss affects large numbers of civilians. The increasing number of patients with TBI-related vision loss necessitated the development of an innovative program which combined elements of therapies that the literature suggested were most promising. In this paper we briefly review the literature, describe the rehabilitation program developed, and present case studies of two patients who incurred vision loss as a result of a motor vehicle accident and a gunshot wound. The intent of the article is to begin the documentation of our ongoing, evidence based neurological vision loss rehabilitation program. We also encourage others who do not currently do so to assess the need for implementing vision rehabilitation programs for patients with TBI-related vision loss.
Keywords: neurological vision loss, comprehensive neurological vision rehabilitation (CNVR)

Introduction

Hemianopsia and other field losses often occur with an acquired brain injury (ABI)^1,2 and recent studies of troops injured while deployed in Iraq and Afghanistan have highlighted the clinical and research importance of these visual deficits.^3–5 Unfortunately, many severe field losses associated with brain injury go undetected.⁶  The reasons for this have not been examined in depth; however the heterogeneity of the population makes large scale, controlled studies difficult. In brain injury rehabilitation settings clinicians often emphasize visual acuity, which may be within the normal range in cases of hemianopsia (particularly with macular splitting or sparring), and comprehensive visual fields may not be routinely performed. A recent study by Rowe and colleagues⁷ reports that by using a standardized screening 92% of patients referred for an eye examination were found to have a visual impairment of some form. Our clinical experience suggests that confrontation fields, one of the most commonly used field assessments in brain injury centers, is not a reliable predictor of field loss. Indeed we have had patients who have no visual field loss indicated on their medical records after confrontation testing, present with a hemianopsia when tested with a Goldmann or Humphrey perimeter. Thus referrals in suspected cases of visual impairment following stroke appears to be warranted. Given that referrals for vision examinations are not a widely applied standard of care,⁷ it is not surprising that the prevalence of visual field loss following ABI has not been well established, although some estimates place the rate as high as 40%.⁸

 Hemianopsia is one of the most common disorders following brain injury ^7,9 affecting mobility, reading, driving, and activities of daily life, presenting patients and caregivers with signif icant challenges. Successful rehabilitation reportedly improves subjective quality of life, and restoration of the ability to perform activities of daily living including educational and occupational tasks, and may, in appropriate cases, allow the individual to drive.^10,11 Given the level of deficit created by hemianopsia and the value of therapy there has been considerable clinical interest in developing effective rehabilitative strategies.^12,13

No single rehabilitative technique for visual field loss following an ABI has achieved widespread acceptance due, in large part, to a lack of controlled research ^14,15 and the heterogeneity of the population which makes such studies difficult. Still, a variety of techniques have been proposed including prisms, vision restoration therapy, and scanning therapy, and we will briefly review these.

Prisms are used to relocate the visual image from the lost visual field to the intact field. Perhaps the first use of prisms to treat hemianopsia dates to Young’s work in 1929.¹⁶ In the intervening years prisms have progressed to improved uses of Fresnel lenses ^11,17–20 and to more sophisticated prism placements.^19,21 While prisms have been found to be helpful to some patients the success rate in the multicenter trial conducted by Bowers, et al ranged from 27% to 81% when used to improve general mobility. Studies that have reported success in patient utilization of prisms also report that some patients discontinue their use after a period of time²² and the reasons for discontinuation warrant further study.

While prisms relocate the visual image to intact areas of the retina, vision restoration therapy (VRT) seeks to decrease the size of the hemianopic area by capitalizing on brain plasticity to restore vision on the border of the hemianopic field.²³ VRT is implemented on a computer viewed by the patient using a head-mount to minimize head motion (www.novavision.com). A fixation spot is used to minimize eye movements and stimuli are presented in both the seeing and nonseeing fields. Training is done in the home during two 30-minute sessions six days per week over a 3 to 6 month time period. As patients progress through the VRT sequence the training program is appropriately modified to match the current abilities of the patient. Improvements have been noted as decreases in the border of the hemianopic field of 5 degrees on average, with a range of 0 to 20 degrees,^23–26 although not all studies have found improvement.²⁷

From Eye and Brain, 2010;2 47-55, Dove MedicalPress, Ltd. An Open Access article which permits unrestricted noncommercial use, provided the original work is properly cited.

 Comments

There are currently no comments for this article