Diopsys Presents: A Primer in use of Visual Evoked Potentials VEP For TBI and Other Neurologically C

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Diopsys PresentsA Primer in use of Visual
Evoked Potentials (VEP) For TBI and Other
Neurologically Challenged Populations

• William V. Padula,OD, FAAO, FNORA
• March 31 2008

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Traditional Use Of VEP

• Diagnosis of afferent sensory nerve loss from
  ocular and nerve pathology (i.e.. macular
  degeneration, glaucoma, optic nerve atrophy,
  etc.) - monocular
• Diagnosis of afferent sensory nerve dysfunction
  from amblyopia - monocular
• Differential diagnosis of refractive asymmetries
  - monocular

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Recent Advances in Use of VEP

• Differential diagnosis of Post Trauma Vision
  Syndrome (PTVS)
• -Padula, Argyris and Ray (1994)
• -Sarno, et. al. (1999)
• -Hellerstein, et. al. (1997)

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VEP

• Sweep analysis
• - Monocular
• - Contrast sensitivity
• - Visual acuity
• Cross pattern reversal
• - Monocular or binocular
• - P-100

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Binocular VEP Evaluation of PTVS

• Amplitude
• Negative Wave
• Background wave consistency

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Neurotoxicity

• Potassium adflux
• Calcium influx
• Cellular proteate enzymes
• Cytoskelatal collapse
• Deafferentation etiologic to PTVS

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Characteristics of P-100

• Binocular testing
• - Amplitude increase
• - Decrease negative amplitude
• - Decrease background noise

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Case 1 C.T.

• Male - 45 yr.
• Rear ended MVA with whiplash
• MRI negative
• Conscious but became spatially disoriented
  following day
• Balance unstable
• Photophobia

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History Cont.

• Unable to read due to words moving and
  jumbling
• Sits in hospital room in darkness
• Occasional diplopia
• Balance varies

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Examination Results

• Habitual Rx None
• VA Distance monocular and binocular - 20/20 to
  20/30 (varies)
• Near monocular and binocular - 20/30 (varies
  with intermittent diplopia)
• Eye health unremarkable
• Sensorimotor eval
• Pursuits lagging fixation with jerky quality
• CNP 8/18
• Phoria 12-16 exo _at_ near
• Red Lens Test diplopia
• Photophobia

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Exam Cont.

• Refraction
• OD Plano
• OS Plano
• Phoria 12-16 exo
• Ductions at near Base Out x / 5/ -8

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Exam Cont. (C.T.)

• Bell Retinoscopy
• -OD/OS 10/12 (varies)
• -Reports two wands intermittently
• -With 1.00 OU 14/15 (intermittent diplopia)
• Visual Midline Assessment
• -Variable
• Walking balance varied and unstable

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Rule Out PTVS - VEP

• Rx
• OD Plano with 2 prism in
• OS Plano with 2 prism in

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Binocular VEP no Rx

• Appears to be a normal P-100
• Amplitude and latency appear appropriate
• No negative wave potential
• Limited background noise

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Positive Test for PTVS

• Amplitude increases with base in prism and
  binasal occlusion

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Treatment

• Rx
• OD Plano with 2 prism base in
• OD Plano with 2 prism base in
• add 1.00
• Binasal occlusion

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Results 1 month

• Photophobia reduced
• CNP 4/8
• Eye strain reduced
• No diplopia
• Words no longer move or jumble when reading
• Balance more stable

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Positive Test for PTVS

• With base in prism OU and binasal occlusion there
  is an increased amplitude

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Case 2History N. R.

• Female- 63 yr
• Broadsided MVA
• Amnesia - unconscious 10 min
• Diplopia inferior field
• Reading - loses place and must hold print at eye
  level
• Balance varies

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Exam Results (N. R.)

• Hab. Rx OD -5.50, OS -4.25
• VA Dist. 20/20 mono-bino
• Near 20/30 (at eye level)
• Eye health unremarkable
• Sensorimotor eval
• -Pursuits diplopia inferior field

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Eval. Cont.

• Phoria Near- 12 exo with 2 BD OS
• CNP - 10/ 14
• Refraction OD -5.50 / OS -4.25
• 15 x / 3 / -6 (low base out reserves)

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Visual Midline Assessment

• Variable with shift to left
• Walking
• - cane in rt. Hand
• -leans and drifts lt.
• Prism OD 2 prism dn and out _at_ 210
• OS 3 prism in
• - (no lean or drift)

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Rule out PTVS - VEP

• Rx
• OD -5.50 with 2 BO
• OS -4.25 with 3 BI and DN _at_ 210

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Binocular VEP with Habitual Rx

• Increased background noise
• Negative wave potential
• Limited amplitude of P-100

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Positive Test for PTVS

• Decreased background noise
• Increased amplitude of P-100
• Decreased negative wave potential

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Treatment

• Rx
• OD -5.50 with 2 prism out and dn _at_ 210
• OS -4.25 with 3 prism in
• add 2.50
• Bi-nasal oclusion

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Results 3 months

• Reduced symptoms of
• - eye strain and improved infra-duction
• - photophobia
• - difficulties with balance
• - diplopia

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Summary

• VEP is effective for monocular evaluation of
• - Pathology affecting afferent nerve function
• - Amblyopia
• - Refractive Assymmetries

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Summary Cont.

• VEP effective for binocular evaluation of
• -Post Trauma Vision Syndrome(PTVS)

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Positive PTVS P-100 Charachteristics

• With addition of base in prism and secondary
  trial with binasal occlusion
• - Increased amplitude
• - Decreased negative wave potential
• - Decreased background noise in resting
  potential

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Amblyopia

• Graph illustrates OD vs OS responses with varying
  stimulus size
• OS gtOD amplitude
• Distinct timing differences across all stimuli
• Dx amblyopia

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Refractive Asymmetry

• Graph illustrates OD vs OS responses with varying
  stimulus size
• OD gtOS amplitude
• Timing equivalent
• Dx Refractive asymmetries w/o amblyopia

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Add Correction

• Objective measurement of introduction of lens
• Brown graph illustrates baseline VEP
• Green represents introduction of corrective lens

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William V. Padula OD, FAAO, FNORAPadula
Institute of Vision RehabilitationPO Box
1408Guilford, CT 06437e-mail
wpadula_at_padulainstitute.com(203)-453-2222