Altered Spontaneous Brain Activity in Adolescents and Adults with Comitant Strabismus and Strabismic Amblyopia

Neuroimaging studies have established that strabismus and amblyopia are associated with structural and functional brain alterations. However, differences in spontaneous brain activity between strabismus patients with and without amblyopia remain unclear. This study employed fractional amplitude of low-frequency fluctuation (fALFF), a normalized version of the amplitude of low-frequency fluctuation that reduces physiological noise and improves detection of spontaneous brain activity, to examine spontaneous brain activity patterns in comitant strabismus (CS) and strabismic amblyopia (SA) patients in adolescents and adults.

Cross-sectional study.

Seventeen patients with CS (10 males and 7 females; mean age, 24.41 ± 6.70 years), 19 patients with SA (9 males and 10 females; mean age, 24.53 ± 6.12 years), and 22 normal controls (12 males and 10 females; mean age, 22.29 ± 3.93 years) were recruited.

Resting-state functional magnetic resonance imaging was performed.

Spontaneous brain activity was assessed using fALFF. Pearson correlation analysis was employed to examine the relationships between fALFF values in altered brain regions and clinical manifestations. Additionally, receiver operating characteristic curve analysis was conducted to descriptively evaluate the discriminatory capacity of fALFF signals between SA and CS patients in this exploratory sample.

Compared with normal controls, both CS and SA patients showed widespread fALFF alterations in visual, sensorimotor, and higher-order cognitive regions. Relative to CS patients, SA patients showed reduced fALFF in the bilateral frontal lobes and elevated fALFF in the left precentral gyrus. An exploratory analysis revealed that fALFF values in the left middle frontal gyrus of SA patients were negatively correlated with the best-corrected visual acuity of the amblyopic eye (r = -0.49, nominal P = 0.033). Receiver operating characteristic analysis using left middle frontal gyrus fALFF yielded an apparent area under the curve of 0.81 for discriminating SA from CS in this sample.

Patients with CS and SA demonstrate distinct patterns of abnormal spontaneous brain activity. Exploratory associations, particularly in the frontal lobe, were observed with visual acuity loss in amblyopia and may be associated with differing neuropathological states between the 2 conditions. These findings provide neuroimaging evidence that contributes to the understanding of strabismus and amblyopia pathophysiology and may inform future research into neural markers of disease progression.

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