Visual-Perceptual alteration in congenital strabismus

Abstract

Because of the important sensory-motor balanceloss in strabismic patients, through this study, we triedto establish a relationship between visual-perceptual difficultiesmost often presented in strabismus and alteration on cortical level.This study has immediate application in the area of visual rehabilitation as it sheds light on the damage to intra and inter-hemispheric connection pathways.

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Tuesday 23 August 2016 16:45 – 17:00
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Visual-perceptual alteration
in congenital strabismus
Danjela Ibrahimi1* and Martin Gallegos-Duarte1
1Department of Optometry, Autonomous University of Queretaro, Queretaro, Mexico
*Corresponding author: mariposa_ib@windowslive.com
Because of the important sensory-motor balance loss in strabismic patients, through this
study, we tried to establish a relationship between visual-perceptual difficulties most
often presented in strabismus and alteration on cortical level. This study has immediate
application in the area of visual rehabilitation as it sheds light on the damage to intra
and inter-hemispheric connection pathways.
Keywords: Strabismus; Cortical Coherences; Brain Waves, Visual-Perceptual Skills
Introduction
The primary seat of Congenital Strabismus (CS) is injury to the white substance (WS), where the
axons of visual pathways, intra and inter-hemispheric circuits are contained. Damage to these
interconnection pathways of long and short fibres that define cerebral cortex can explain the
heterogeneity of presentation of the clinical manifestations. The central integrator loses control,
allows the exacerbation of some reflexes that cannot be controlled by the cerebral cortex, inhibiting
this way some perceptual and sensory skills that characterize the disease. This sensory-motor
balance loss is the main feature of Congenital Strabismus. Thanks to this research we could be able
to define the most affected areas of visual-perceptual skills according to the type of strabismus
(associated or dissociated) and try to relate brain areas with waves, based on the results of DBM
(Digitized Brain Mapping).
Methods
This is a retrospective, descriptive and observational study in a cohort of children between 5 and 16
years old. All patients underwent an optometric examination based on the 21 points of (OEP)
Optometric Extension Program. A detailed Visual-Perceptual Analysis including TVPS (Test of
Visual-Perceptual Skills), VMI (Visual-Motor Integration) (Tables 1 and 2), Memory of MONROE,
Directionality of GARDNER, VADS (Visual-Aural Digital Span) and DEM (Development Eye
Movement Test) was performed to each one of them. The obtained values were correlated with the
type of congenital strabismus (CS) and the alterations found in the Digitized Brain Mapping (DBM).
Coherences obtained in "Z" normative values were processed and the minimum, maximum, average
values, the sum and number of patients who had abnormalities on a certain pathway was calculated.
Pathways with major alteration and the most affected brain waves were identified, in order to
correlate these findings with the clinical diagnosis (Tables 2 and 3).

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Table 1: Visual-perceptual and visual-motor abilities at exotropia and dissociated horizontal deviation
Exotropia
Dissociated horizontal deviation
TVPS
Sum
Average
Sum
Average
Visual Discrimination
Memory
Spatial Relations
Form Constancy
Sequential Memory
Figure Ground
Visual Closure
7
8
9
8
7
9
8
–26.71
–25.34
–23.1
–31.36
–16.99
–21.14
–18.43
–3.8
–3.2
–2.6
–3.9
–2.5
–2.4
–2.3
3
3
3
3
2
3
3
–21.95
–15.81
–15.85
–19.88
–10.51
–23.90
–14.95
–7.32
–5.27
–5.28
–6.62
–5.25
–7.96
–4.98
VMI
Sum
Average
Sum
Average
VMI
Perception
Motor
6
8
7
–14.46
–37.18
–32.32
–2.4
–4.7
–4.6
3
3
3
–4.96
–7.76
–6.77
–1.65
–2.58
–2.26
Results
62 patients diagnosed with Congenital Strabismus (27 women and 36 men) were obtained. 50%
diagnosed with Congenital Esotropia (ETC), 30% with Exotropia (XT) and 20% presented
Dissociated Strabismus (ED). Visual-Perceptual alterations were found throughout the sample.
Figure 1 shows the results obtained from the studies of TVPS and VMI of all three categories.
Above each column is shown the divergence in years from the norm of each skill.
The study showed that the most affected cortical areas in the whole sample were P4T6 (parietal-
temporal of right hemisphere) and FP1FP2 (frontal-parietal of left and right hemisphere
respectively); 83.33% of Esotropias had P4T6 affected and 66.6% FP1FP2; 100% of patients with
Exotropia had FP1FP2 affected and 60% P4T6; 75% of patients with dissociated strabismus had
P4T6 affected and 50% FP1FP2.
Table 2: Hypo-coherence of inter-hemispheric connectivity of right hemisphere
Parameter
Delta
Theta
Alfa
Beta
P4T6
Number
16
16
11
11
P4T6
Minimum
–8
–7.67
–5.13
–4.28
P4T6
Maximum
–2.3
–2.1
–2.1
–2.19
P4T6
Sum
–52.5
–54.4
–35.62
–30.87
P4T6
Average
–3.3
–3.4
–3.24
–2.80
Table 3: Hypo-coherence of inter-hemispheric connectivity, left hemisphere-right hemisphere
Parameter
Delta
Theta
Alfa
Beta
FP1FP2
Number
11
12
6
2
FP1FP2
Minimum
–9.03
–4.4
–3.41
–4.73
FP1FP2
Maximum
–2.05
–2.18
–2.04
–2.31
FP1FP2
Sum
–44.78
–35.36
–15.16
–7.04
FP1FP2
Average
–4.07
–2.95
–2.53
–3.52

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Figure 1 (left):divergence in age of visual- perceptual skills (TVPS) and visual-motor integration (VMI) at
patient with exotropia (XT), congenital esotropia (ETC) and dissociated strabismus (ED).
Figure 2 (right): Brain waves Delta (D) - Theta (T) and their relationship with cortical areas P4T6-FP1FP2
Figure 2 shows that there is a predominance of Delta wave at P4T6 and Theta at FP1FP2.
Regarding the rest of Visual-Perceptual Analysis, the greatest deviation at the Memory of
MONROE test was found in dissociated strabismus with a divergence of 3 years and 9 months from
the expected age. As far as Eye Movements test, Types 2 (oculomotor dysfunction) and 4
(deficiencies in automaticity and oculomotor skills) were the most frequented in whole sample.
Patients with congenital esotropia presented greater directionality problems, reaching only 17.7%.
Both visual and aural pathways showed deficiencies in all three categories of strabismus.
Conclusions
The analysis shows that visual-perceptual alterations found in congenital strabismus are possibly
due to a deficiency in the parietal-temporal and frontal-parietal connectivity (there is a relationship
of hypo-coherence between intra and inter-hemispheric areas). Alterations in delta and theta waves
found in the sample are indicative of cortical immaturity which could be related to these findings.
The more dissociated a strabismus, more visual-perceptual alterations are involved. We found that
the most affected areas in the brain correspond to the most affected skills during visual-perceptual
analysis.
References
1 Engle EC. Genetic basis of congenital strabismus. Arch Ophthalmol. 2007;125(2):189.
2 Gallegos-Duarte M. Estigma y origen de la endotropia congénita. Rev Mex Oftalmol.2005;79(1):10–16.
3 Gallegos-Duarte M, Mendiola-Santibañez J, Saldaña C. Alteraciones de la sustancia blanca en el estrabismo congénito
esencial. Estudio neurofuncional y morfométrico. Acta Estrabologica. Acta Estrabológica. 2012;51(1):13-40.
4 Greenberg AE, Mohney BG, Diehl NN, Burke JP. Incidence and Types of Childhood Esotropia. Ophthalmology.
2007;114(1):170–4
5 Knyazeva MG. (2013). Splenium of Corpus Callosum: Patterns of interhemispheric interaction in children and adults.
Neural Plasticity. 2013;1–12 (doi:10.1155/2013/639430).
Visual-perceptual analysis
XTa
ETC
ED
Relationship between cortical areas
and brain waves