Binocularity and spatial frequency dependence of calcarine activation in two types of amblyopia.
OBJECTIVE
Strabismus and anisometropia early in life frequently causes monocular amblyopia. Activation of the visual cortex is compared between the two types of amblyopia to elucidate differences in the pathogenetic mechanism of the disease.


METHODS
Using an EPI gradient echo sequence in 1.5T MRI, calcarine activation by monocular viewing of checkerboard patterns with reversal was examined in terms of binocularity of the activation and dependence on the spatial frequency of the stimuli.


RESULTS
First, the proportion of voxels activated by both normal and amblyopic eye monocular stimulations is lower in the strabismic group than in the anisometropic group. Second, the activation by higher-spatial-frequency stimuli is reduced in the anisometropic group, but not in the strabismic group.


CONCLUSIONS
These findings from the human visual cortex are consistent with the view proposed based on animal research that the loss of binocular interaction and the undersampling of high-spatial-frequency components of visual stimuli are each one of the underlying changes in strabismic and anisometropic amblyopia, respectively.
Lee
K M
KM
Department of Neurology, Seoul National University, 110-744, Seoul, South Korea. kminlee@snu.ac.kr
Lee
S H
SH
Kim
N Y
NY
Kim
C Y
CY
Sohn
J W
JW
Choi
M Y
MY
Gyu Choi
D
D
Hwang
J M
JM
Ho Park
K
K
Lee
D S
DS
Suk Yu
Y
Y
Hyun Chang
K
K
D000293:Adolescent; D000328:Adult; D000550:Amblyopia / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D015858:Anisometropia / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D013028:Space Perception / Q000502:physiology*; D013285:Strabismus / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D015348:Vision, Binocular / Q000502:physiology*; D014793:Visual Cortex / Q000473:pathology / Q000503:physiopathology*