Neera Kapoor

The frequency of occurrence, types, and characteristics of visual field defects in acquired brain injury: a retrospective analysis.

BACKGROUNDnThe purpose of this retrospective study was to determine the frequency of occurrence of visual field defects in a sample of visually symptomatic, ambulatory outpatients who have acquired brain injury (ABI), either traumatic brain injury (TBI) or cerebral vascular accident (CVA).nnnMETHODSnThe medical records of 220 individuals with TBI (n=160) or CVA (n=60) were reviewed retrospectively. This was determined by a computer-based query spanning the years 2000 through 2003. The individuals records were reviewed to determine the frequency of targeted visual field defects that were classified as scattered, restricted, homonymous, nonhomonymous, and visual neglect. The altitudinal and lateral characteristics of these defects were also determined.nnnRESULTSnIn the total ABI sample of 220, some 102 (46.36%) individuals had 1 of the targeted defects diagnosed. These defects were present in 62 (38.75%) of the TBI subgroup and in 40 (66.67%) of the CVA subgroup. The most frequent defects in the TBI group were scattered (58.06%) followed by homonymous (22.58%). In the CVA group, the most numerous were homonymous (47.5%), with scattered and nonhomonymous accounting for 20% each.nnnCONCLUSIONnThe uniqueness of the current study is that it reports the frequency of occurrence of specified visual field defects in the total ABI sample and in the TBI and CVA subgroups. This enabled comparisons with other studies that generally have reported on just 1 of these groupings. The current results are in accord with most of the other studies that are reviewed. The findings of this study should alert the reader to the high frequency of occurrence of visual field defects in the ABI population, and make the reader aware of the adverse effects they can have on quality of life and rehabilitation.

Accommodation in mild traumatic brain injury

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.

Oculomotor neurorehabilitation for reading in mild traumatic brain injury (mTBI): An integrative approach

BACKGROUNDnConsidering the extensive neural network of the oculomotor subsystems, traumatic brain injury (TBI) could affect oculomotor control and related reading dysfunction.nnnOBJECTIVEnTo evaluate comprehensively the effect of oculomotor-based vision rehabilitation (OBVR) in individuals with mTBI.nnnMETHODSnTwelve 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.nnnRESULTSnFollowing 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.nnnCONCLUSIONSnOBVR 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 in mild traumatic brain injury: A pilot study

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.

Elevated dark adaptation thresholds in traumatic brain injury

Primary objective: To expand upon earlier findings of elevated dark adaptation (scotopic) thresholds in photosensitive individuals with traumatic brain injury (TBI). Methods and procedures: To assess scotopic thresholds in individuals with TBI (nu2009=u200917) manifesting varying degrees of photosensitivity (mild, moderate or marked), but without retinal dysfunction, to those of non-photosensitive, visually-normal individuals (nu2009=u200921) using a hand-held dark adaptometer. Main outcomes and results: The group mean scotopic threshold for the TBI group was significantly higher than that of the visually-normal group. Over 50% (nine out of 17) of the TBI group exhibited elevated thresholds. There was no correlation between the threshold value and degree of photosensitivity. Conclusion: The elevated scotopic thresholds suggest an abnormality in cortical gain control. An anomalous adaptive response may develop due to cortical damage, thereby attenuating subjective light sensation.

Occurrence of ocular disease in traumatic brain injury in a selected sample: A retrospective analysis

Primary objective: To determine retrospectively the relative risk of ocular disease in a selected, visually-symptomatic sample of clinic patients having traumatic brain injury (TBI; nu2009=u2009160) vs. cerebrovascular accident (CVA; nu2009=u200960), with all initially presenting at the clinic with symptoms and/or signs of vision dysfunction. Methods and procedures: To review retrospectively 220 medical records of individuals with TBI (nu2009=u2009160) vs. CVA (nu2009=u200960), as determined by a computer-based query spanning the years 2000–2003, to ascertain the frequency of occurrence of ocular disease in the two major sub-groups of acquired brain injury. Main outcomes and results: Conditions with high relative risk unique to TBI included corneal abrasion, blepharitis, chalazion/hordeolum, dry eye, traumatic cataract, vitreal prolapse and optic atrophy. This is distinct from those ophthalmic conditions unique to CVA, which included sub-conjunctival haemorrhage and ptosis. Conclusion: These new findings should alert clinicians to the potential increased frequency of occurrence of specific ocular diseases in a selected, visually-symptomatic population with TBI and their associated rehabilitative and quality-of-life implications.

Elevated coherent motion thresholds in mild traumatic brain injury.

PURPOSEnIndividuals 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.nnnMETHODSnFourteen 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.nnnRESULTSnMean 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.nnnCONCLUSIONSnThe 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.

Foveal versus eccentric retinal critical flicker frequency in mild traumatic brain injury

BACKGROUNDnThe 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).nnnMETHODSnMean 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.nnnRESULTSnThere 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.nnnCONCLUSIONSnDecreased sensitivity and increased variability in CFF measurements in the TBI population can be attributed to damage to the higher visual pathways.

Static and dynamic aspects of accommodation in mild traumatic brain injury: a review.

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.

Temporal characteristics of proximally-induced accommodation.

This study sought to determine whether proximally‐induced accommodation (PIA) is capable of sustaining an accommodative response over time. Accordingly, the steady‐stale PIA response was measured during the course of a continuous 5 min stimulus period for targets located at distances of 0.2 or 6 m. The vergence und accommodation loops were opened by subjects (n= 8) monocularly viewing the targets through a 0.5 mm pinhole, while accommodation was assessed using an objective, open‐field, infrared optometer. The mean PIA response did not change significantly during the fixation period. This finding suggests that PIA is indeed capable of maintaining a sustained response. This observation is consistent with the constancy of apparent target distance perception during extended fixation of a stationary object of regard under these conditions.