Evaluation of the functions of the parvocellular and magnocellular pathways in strabismic amblyopia.

PURPOSE

To evaluate the functions of the magnocellular and parvocellular pathways in strabismic amblyopia.

METHODS

Visual evoked potentials produced by achromatic and chromatic stimuli in 14 children with strabismic amblyopia were compared with those in 14 age-matched control subjects. The achromatic sine-wave grating with low spatial frequency was used to stimulate the magnocellular pathway, whereas the parvocellular pathway was stimulated by the chromatic sine-wave grating (isoluminant red-green) with low and high spatial frequencies.

RESULTS

When the achromatic stimuli with low spatial frequency were used, the latencies of the N1 and P1 components and the amplitude of the N1-P1 complex were similar in the children with strabismic amblyopia and the control subjects. There also were no differences between the amblyopic and non-amblyopic eyes of the children with strabismic amblyopia. When chromatic stimuli with low and high spatial frequencies were used, the latencies of the N1 and P1 components were significantly longer and the amplitude of the N1-P1 complex was significantly smaller in the children with strabismic amblyopia than in the control group. When the amblyopic and non-amblyopic eyes of the children with strabismic amblyopia were compared, the latencies of the N1 and P1 components were longer and the amplitude of the N1-P1 complex was smaller in the amblyopic eyes.

CONCLUSION

In strabismic amblyopia, the cells in the parvocellular pathway may be more involved, whereas the magnocellular pathway may be relatively spared.