Reading Deficits after a TBI: Is Vision Part of the Problem?

David H. Biberdorf, OD, FCOVD

Post-Concussion Vision Problems

• 90% of all concussions will have 1 or more ocular problems

• Symptoms may include light sensitivity, headaches, eyestrain, blurred vision, double vision, motion sensitivity, disequilibrium, reading problems

• Hidden vision problems frequently persist 6-9 months after a concussion

What does CDC say about Concussions and RTL?• Effects of mTBI include poor self-regulation, reduced executive

function, attention difficulties, information processing problems, memory problems, inconsistent learning, knowledge gaps, lower educational attainment, social-behavioral problems, poor peer relationships, and reduced social adjustment skills

• Specifics to “reading” are lacking

What does CDC say about Return To School Guidelines?• To date, there has been no systematic evaluation of any return to

school models. CDC is currently examining a range of promising programs that provide a healthcare-to-school linkage to better understand the processes that are optimal in ensuring children with a TBI are monitored after they return to school and receive appropriate accommodations and/or services.

When is the Visual System Ready to Read?

Visual Hardware

Visual Software

3 Main Oculomotor Skills Used in Reading

• Vergence: Accurate binocular fusion on text material

• Accommodation: Accurate focusing on text material

• Versions (Saccades): Accurate synchronized tracking along text material

A number of subjective and optometric tools are used to measure these functions.

Vision and Reading Deficits in Post-Concussion Patients: A Retrospective Analysis Tannen, et al. Vis. Dev. & Rehab. 2015;1:(3) 206-212. • 25 consecutive post-concussion patients

• 56% convergence insufficiency

• 75% accommodative insufficiency

• 68-82% oculomotor-based reading dysfunctions

• 84% had headaches (25% associated with reading)

• 68% reading 2 grade levels below current school grade level

Convergence Insufficiency Symptom Survey (CISS)

Visagraph/Readalyzer: A Tool which gives objective real-time Information about saccadic and vergence functions during reading

Visagraph/Readalyzer Normed Data

• Number of Fixations: Forward eye movements

• Number of Regressions: Backward eye movements

• Average Duration of Fixation

• Reading Speed in Words per Minute

• Grade Level Equivalent: Composite of all measures

• Anomalies (eyes moved in opposite direction)

• Cross-Correlations (percent the two eyes are synchronized when moving in same direction)

Tannen & Ciuffreda Visagraph Protocol for mTBI1.) Pt reads grade level text (e.g. grade level 10; comprehension at least 70%)2.) Pt reads 5 levels below grade level text (e.g. grade level 5; comprehension

at least 70%) 3.) If increase Grade Level Equivalent (GLE) less than 3 grades, oculo-

motor dysfunction suspected4.) Longer duration of fixation is typical of mTBI5.) Cross‐correlation(symmetry) and Anomalies (opposite eye movements)

are indicators of poor eye teaming 5.) Normative Data; Good sensitivity; Lacks specificity6.) Good for monitoring student‐athletes’ vision recovery/rehabilitation for

return‐to‐learn

Case Study

• O.G. is a 21 y/o UND soccer player with SRC 4 months prior

• Symptoms of headaches, vision discomfort, light sensitivity, reading difficulty, computer screen bothersome. CISS score 48.

• Visual Hardware (oculomotor) problems: Convergence insufficiency; accommodative insufficiency; saccadic dysfunction

• Severely reduced Visagraph/Readalyzer scores

• Underwent 3 months of oculomotor rehabilitation

• After 3 months, oculmotor skills still not completely automated, but symptoms improving

Grade 10 Level Text Initial Visit

Grade 5 level text initial visit

Grade 10 level text after 3 months oculomotor therapy

Grade 5 level text after 3 months oculomotor therapy

What about Visual Software and Reading?

Visual Software

Magnocellular Theory of Developmental Dyslexia• Measures of magnocellular function, such as coherent motion

thresholds, and critical flicker fusion, and VEP show temporal dysfunction of visual processing (magnocellular system). This has lead to the Magnocellular Theory of Developmental Dyslexia

• May be the cause of reports of print moving during reading, fixationalinstability

• Does this same dysfunction occur in post-concussion patients?

Subjective non-oculomotor, magnocellular processing tests: OG’s initial results• Elevated Coherent Motion Threshold:

(>10% significant)

• Elevated CFF:

(>50Hz significant)

VEP: Parvo vs. Magno latency responses

Objective VEP measures of magnocellular processing show latency delay for OG which improved only slightly after 3 months

Dynamic Cognitive Remediation for Traumatic Brain Injuries Significantly Improves Attention, Working Memory, Processing Speed, and Reading Fluency Lawton & Huang 2018• 4 TBI patients, aged 5, 50, 62, and 68 years old

• 6-12 weeks of visual timing intervention, PATH to Insight (PATH) neuro-training; 2-3 sessions/week; 20-30 min sessions

• Training improved motion discrimination discrimination, reading performance, cognitive functioning, MEG brain imaging, attention the attention and executive control networks

www.pathtoinsight.com

Conclusions

• Visual Hardware (oculomotor) and visual software problems are common after mTBI

• Many vision problems can persist and can rob the cognitive domains of limited attentional resources, impeding reading and learning

• Current RTL guidelines are few and non-uniform

• Tools such as CISS questionnaire and Visagraph/Readalyzer may help in RTL decision-making

• Visual hardware (oculomotor) rehabilitation will likely improve both symptoms and oculomotor performance that affect reading

• Future research will show if visual software (magnocellular processing) rehabilitation may also improve reading performance