Faculty Bibliography

PURPOSE/OBJECTIVE:This pilot study sought to determine the efficacy of using the Developmental Eye Movement (DEM) test in the adult, acquired brain injury (ABI) population to quantify clinically the effects of controlled, laboratory-performed, oculomotor-based vision therapy/vision rehabilitation. METHODS:Nine adult subjects with mild traumatic brain injury (mTBI) and five with stroke were assessed before and after an eight-week, computer-based, versional oculomotor (fixation, saccades, pursuit, and simulated reading) training program (9.6h total). The protocol incorporated a cross-over, interventional design with and without the addition of auditory feedback regarding two-dimensional eye position. The clinical outcome measure was the Developmental Eye Movement (DEM) test score (ratio, errors) taken before, midway, and immediately following training. RESULTS:For the DEM ratio parameter, improvements were found in 80-89% of the subjects. For the DEM error parameter, improvements were found in 100% of the subjects. Incorporation of the auditory feedback component revealed a trend toward enhanced performance. The findings were similar for both DEM parameters, as well as for incorporation of the auditory feedback, in both diagnostic groups. DISCUSSION/CONCLUSIONS:The results of the present study demonstrated considerable improvements in the DEM test scores following the oculomotor-based training, thus reflecting more time-optimal and accurate saccadic tracking after the training. The DEM test should be considered as another clinical test of global saccadic tracking performance in the ABI population.

BACKGROUND: Considering the extensive neural network of the oculomotor subsystems, traumatic brain injury (TBI) could affect oculomotor control and related reading dysfunction. OBJECTIVE: To evaluate comprehensively the effect of oculomotor-based vision rehabilitation (OBVR) in individuals with mTBI. METHODS: Twelve subjects with mTBI participated in a cross-over, interventional study involving oculomotor training (OMT) and sham training (ST). Each training was performed for 6 weeks, 2 sessions a week. During each training session, all three oculomotor subsystems (vergence/accommodation/version) were trained in a randomized order across sessions. All laboratory and clinical parameters were determined before and after OMT and ST. In addition, nearvision-related symptoms using the Convergence Insufficiency Symptom Survey (CISS) scale and subjective visual attention using the Visual Search and Attention Test (VSAT) were assessed. RESULTS: Following the OMT, over 80% of the abnormal parameters significantly improved. Reading rate, along with the amplitudes of vergence and accommodation, improved markedly. Saccadic eye movements demonstrated enhanced rhythmicity and accuracy. The improved reading-related oculomotor behavior was reflected in reduced symptoms and increased visual attention. None of the parameters changed with ST. CONCLUSIONS: OBVR had a strong positive effect on oculomotor control, reading rate, and overall reading ability. This oculomotor learning effect suggests considerable residual neuroplasticity following mTBI.

Vergence dysfunction in individuals with mild traumatic brain injury (mTBI) may have a negative effect on quality of life, functional abilities, and rehabilitative progress. In this study, we used a range of dynamic and static objective and subjective measures of vergence to assess 21 adult patients with mTBI and nearwork symptoms. The results were compared with 10 control adult subjects. With respect to dynamic parameters, responses in those with mTBI were slowed, variable, and delayed. With respect to static parameters, reduced near point of convergence and restricted near vergence ranges were found in those with mTBI. The present results provide evidence for the substantial adverse effect of mTBI on vergence function.

BACKGROUND: This article reviews literature regarding individuals with traumatic brain injury who have vision related impairments up to one year, post-injury. Such impairments may impact rehabilitation of activities of daily living and mobility since vision is integral in much of what one does on a daily basis. METHODS: Search of Medline, Ovid, and PubMed was performed using terms including: traumatic brain injury, visual deficits after brain injury, vision and traumatic brain injury, and ADLs after brain injury. RESULTS: Eighteen studies were analyzed and reviewed. A range of visual and visual-motor impairments are seen across the severity of traumatic brain injury. Visual impairment negatively impacts independence in mobility and activities of daily living. Common sensorimotor visual symptoms reported by those with traumatic brain injury include blurred vision, reading problems, double vision or eyestrain, dizziness or disequilibrium in visually-crowded environments, visual field defects, light sensitivity, and color blindness. CONCLUSIONS: This review should alert the reader to common visual complaints and defects seen after traumatic brain injury. It is important to screen persons who have suffered traumatic brain injury for sensorimotor vision deficits early on in recovery so that these issues may be addressed and recovery of function and independence in the community are not delayed.

PURPOSE: Individuals with mild traumatic brain injury (mTBI) frequently complain of increased sensitivity to visual motion. Thus, the purpose of this study was to assess the coherent motion threshold (CMT) in subjects with mTBI and reported visual motion sensitivity. METHODS: Fourteen adult subjects with mTBI and symptoms of motion sensitivity were tested. They were compared with 40 age-matched asymptomatic visually normal individuals. CMT was assessed using a 2-alternative, forced choice paradigm. A symptom rating-scale questionnaire related to motion and light sensitivity, vertigo, and self-reported reading ability was also administered to the mTBI group. RESULTS: Mean CMTs were significantly elevated in the mTBI (8.81%) versus the normal subjects (6.53%). There was a trend for a progressive increase in mean CMT in mTBI with increased symptoms related to visual motion sensitivity and vertigo. However, there was no apparent relation to either light sensitivity or self-reported reading ability in mTBI. There was no significant age effect in either group. CONCLUSIONS: The elevated CMT in mTBI suggests damage to the magnocellular pathway, such as extrastriate visual cortical area V5, visual area medial temporal, and the medial superior temporal cortex, which is involved directly in various aspects of motion processing. These findings are consistent with the subjects' symptoms of motion sensitivity and vertigo in their natural environments.

Accommodation refers to the process of obtaining and maintaining a focused foveal retinal image of an object of interest. It involves optical, sensory, motor, perceptual, cognitive, pharmacologic, and biomechanical aspects, and hence represents a complex, multilevel neurologic control process. In patients with mild traumatic brain injury (mTBI), this process frequently is disrupted and compromised neurologically because of the pervasiveness of the coup-contrecoup, swelling, and shearing aspects of the brain injury. In this report, we review the earlier literature on accommodation in mTBI and then present several new findings from our clinical research unit, along with their clinical implications.

Accommodative dysfunction in individuals with mild traumatic brain injury (mTBI) can have a negative impact on quality of life, functional abilities, and rehabilitative progress. In this study, we used a range of dynamic and static objective laboratory and clinical measurements of accommodation to assess 12 adult patients (ages 18-40 years) with mTBI. The results were compared with either 10 control subjects with no visual impairment or normative literature values where available. Regarding the dynamic parameters, responses in those with mTBI were slowed and exhibited fatigue effects. With respect to static parameters, reduced accommodative amplitude and abnormal accommodative interactions were found in those with mTBI. These results provide further evidence for the substantial impact of mTBI on accommodative function. These findings suggest that a range of accommodative tests should be included in the comprehensive vision examination of individuals with mTBI.

BACKGROUND: The purpose of this study was to assess the critical flicker fusion frequency (CFF) at the fovea and at 10 degrees of horizontal retinal eccentricity and to determine if there was a correlation between CFF and the degree of light and motion sensitivity in individuals with mild traumatic brain injury (TBI). METHODS: Mean CFF thresholds at the fovea, and 10 degrees to the left and right of the fovea, were obtained in 14 mild TBI and 29 visually normal subjects. A questionnaire was used to quantify the degree of light and motion sensitivity and related factors. RESULTS: There was no effect of age on CFF under any test condition in either group, nor was there a relation in the TBI group between reported light or motion sensitivity and CFF. Peripheral CFF values were lower in both populations. Among the TBI subjects, there was a trend for lower peripheral CFF values in the periphery and greater mean variability under all 3 test conditions. CONCLUSIONS: Decreased sensitivity and increased variability in CFF measurements in the TBI population can be attributed to damage to the higher visual pathways.