Assessment of Ocular Injury and Visual Function in Veterans with TBI from Combat Blast
Download
1 / 31

Assessment of Ocular Injury and Visual Function in Veterans with TBI from Combat Blast - PowerPoint PPT Presentation


  • 126 Views
  • Uploaded on

Assessment of Ocular Injury and Visual Function in Veterans with TBI from Combat Blast Glenn Cockerham, MD VA Palo Alto Health Care System Palo Alto, California. Presentation Goals. Blast effects on the eye and visual function

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Assessment of Ocular Injury and Visual Function in Veterans with TBI from Combat Blast' - mahdis


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Assessment of Ocular Injury and Visual Function in Veterans with TBI from Combat Blast

Glenn Cockerham, MD

VA Palo Alto Health Care System

Palo Alto, California


Presentation Goals with TBI from Combat Blast

  • Blast effects on the eye and visual function

  • Assessment of eye injury in subjects with traumatic brain injury (TBI) from blast

  • Testing of visual function


Financial disclosures
Financial Disclosures with TBI from Combat Blast

  • NONE


Acknowledgements
Acknowledgements with TBI from Combat Blast

  • Travel support from DoD/VA Vision Center of Excellence

  • Funding support from the Veterans Health Administration by Merit Review Award C5018R


Tbi and blast
TBI and Blast with TBI from Combat Blast

  • Blast most common cause of TBI in Iraq and Afghanistan

  • In 2008 over 300,000 potential TBIs from blast estimated by RAND Corporation, out of 1.2 million U.S. military who had served in Iraq

  • Incidence of closed-globe ocular injury and visual dysfunction unknown

  • Okie S. Traumatic brain injury in the war zone. N Engl J Med 2005;352:2043-2047.


Blast and the eye
Blast and The Eye with TBI from Combat Blast

  • Blast forces severe enough to cause TBI may injure the eye, adnexa (eyelids), orbit, and optic nerve

  • Eye is vulnerable to frontal (and other vectors?) overpressure, stress waves and shear waves

  • Visual dysfunction possible from eye, optic nerve or central damage


Anatomic evaluation of the eye after blast injury
Anatomic Evaluation of the Eye after Blast Injury with TBI from Combat Blast

  • Ocular examination

  • CT imaging of orbital bones, optic canal

  • MRI of visual pathways, brain

  • Retinal nerve fiber layer by spectral domain optical coherence tomography (OCT)

  • Corneal endothelium density and morphology by specular microscopy


Ocular examination
Ocular Examination with TBI from Combat Blast

  • Closed-globe injury: external or internal damage to eye without penetration or rupture of eye wall

  • Examination visualizes all compartments and tissues of eye

  • Ocular trauma classification divided into anatomic zones

  • Pieramici DJ, et al. A system for classifying mechanical injuries of the eye (globe). Am J Ophthalmol 1997;123:820-831.


Closed globe ocular injury in blast
Closed-globe Ocular Injury in Blast with TBI from Combat Blast

  • 43% of 46 subjects with blast TBI had closed-globe ocular injury

  • No evident protective effect from ballistic eyewear (W = 246.5, Z = -.54, p = .64)

  • Visual acuity not predictive of ocular injury (chi-square = 2.39, p= 0.15)

  • Cockerham GC, et al. Closed-eye ocular injuries in the wars in Iraq and Afghanistan. N Engl J Med 2011;364:2172-2173.




23 Year Old Marine, Right IED Blast, Ballistic Eye Wear: Endothelial Cell Density by Specular Microscopy

Right eye, CD 1207

Left Eye, CD 2681


Tests of visual function
Tests of Visual Function Endothelial Cell Density by Specular Microscopy

  • Psychometric tests

  • Require attention and cooperation

    • Visual acuity

    • Contrast sensitivity

    • Visual fields

    • Accommodation (focus)

    • Color discrimination


Visual acuity
Visual Acuity Endothelial Cell Density by Specular Microscopy

  • Worldwide test for vision for > 100 years

  • Traditionally measured with high-contrast Snellen optotypes

  • 20/20 or 6/6 notation

  • Gold standard for clinical testing and research

ETDRS Chart 100% Contrast


Visual acuity what does it measure
Visual Acuity: What does it measure? Endothelial Cell Density by Specular Microscopy

  • Spatial limit of visual resolution

  • Normal minimal angle of resolution is 30 seconds arc

  • Requirements for optimal vision:

    • Photopic conditions

    • Clear optical media

    • Steady foveal fixation

    • Intact photoreceptors

    • Intact afferent visual pathways


Limitations to standard visual acuity testing
Limitations to Standard Visual Acuity Testing Endothelial Cell Density by Specular Microscopy

  • Uses 100% contrast targets (not real world scenario)

  • Not sensitive to subclinical disorders affecting afferent pathways

  • May be normal in neuro-ophthalmic conditions, such as multiple sclerosis (MS)


Low contrast visual acuity lcva in multiple sclerosis
Low-Contrast Visual Acuity (LCVA) in Multiple Sclerosis Endothelial Cell Density by Specular Microscopy

  • Correlations with LCVA

    • T2 lesion volume (3-mm3 increase per line of vision)

    • OCT RNFL (4 micron decrease per line of vision)

    • Functional scales (EDSS – expanded disability status scale)

2.5% Contrast

Balcer LJ, Frohman EM. Evaluating loss of visual function in multiple sclerosis as measured by low-contrast letter acuity. Neurology 2010;74:S16-S23.


High contrast visual acuity in blast tbi
High-Contrast Visual Acuity in Blast TBI Endothelial Cell Density by Specular Microscopy

  • 55 examinations at baseline

  • 62% were 20/20 or better in both eyes

  • 21% had one eye between 20/25 and 20/40

  • 17% had one eye worse than 20/40


Spatial contrast sensitivity cs
Spatial Contrast Sensitivity (CS) Endothelial Cell Density by Specular Microscopy

  • Light-dark transition at edge of object

  • Contrast is ratio of difference in luminance between areas (0%= no contrast)

  • In CS testing the contrast is varied to determine the threshold (unlike visual acuity, in which the contrast remains the same and the target size varies)


Contrast sensitivity grating tests
Contrast Sensitivity Grating Tests Endothelial Cell Density by Specular Microscopy

  • Sine wave grating patches

  • Illuminated cabinet

  • Different spatial frequencies

  • 3,6,12,18 cycles per degree


Spatial contrast sensitivity in tbi
Spatial Contrast Sensitivity in TBI Endothelial Cell Density by Specular Microscopy

  • 47 tests at baseline examination

  • 47% had CS reduced by 2 SD in at least one eye


Automated perimetry
Automated Perimetry Endothelial Cell Density by Specular Microscopy

  • Tests sensitivity of the visual field

  • Each point on the retina is represented in visual space and can be tested

  • Peak sensitivity in the center of retina (fovea) and decreases towards periphery


Visual field testing in tbi
Visual Field Testing in TBI Endothelial Cell Density by Specular Microscopy

  • Main concern is test duration: full-threshold testing takes about 12 minutes per eye

  • Swedish Interactive Threshold Algorithm (SITA): reduces testing time by half (6 minutes)

  • Frequency-doubling technology (FDT): uses flicker target instead of stationary white stimulus, reduces screening test time to 2 to 3 minutes


Automated Static Perimetry with SITA Algorithm Endothelial Cell Density by Specular Microscopy

Field Depression (Decreased Sensitivity)

Complete Hemianopia of Left Visual Field


Automated perimetry with frequency doubling flicker
Automated Perimetry with Frequency-Doubling (Flicker) Endothelial Cell Density by Specular Microscopy


Automated static perimetry in tbi
Automated Static Perimetry in TBI Endothelial Cell Density by Specular Microscopy

  • 49 reliable tests at baseline examination

  • 63% had significantly reduced mean deviation (reduced field sensitivity) in at least one eye

  • 8 had neurologic scotomas (4 hemianopias, 4 quadrantanopias)


Accommodation
Accommodation Endothelial Cell Density by Specular Microscopy

  • Dynamic change in lens curvature to allow focus on near targets

  • Accommodative triad: accommodation, convergence, and miosis (pupil constriction)

  • Preoccipital cortex, midbrain, oculomotor nuclei

  • Subjective symptoms include eye pain, headache, difficulty with near vision, diplopia


Accommodative testing
Accommodative Testing Endothelial Cell Density by Specular Microscopy

Open Field Analyzer

Accommodative Rule


Summary
Summary Endothelial Cell Density by Specular Microscopy

  • Blast forces may damage eyes and visual pathways

  • Visual function, especially visual acuity, may be relatively normal

  • Further research required for best practices in detecting damage and dysfunctions


Team members
Team Members Endothelial Cell Density by Specular Microscopy

  • Thomas Rice, MD

  • Sonne Lemke, PhD

  • Kimberly Cockerham, MD, FACS

  • Eva Hewes, MD

  • Richard Lin, MD, PhD

  • Gloria Wang, MD

  • Catherine Glynn-Milley, RN, CRNO

  • Lars Zumhagen, MD


ad